This work presents an interrogator system based on an erbium-doped fiber ring cavity for refractive-index measurements. This fiber ring cavity is assisted by a fiber Bragg grating and a phase-shift fiber Bragg grating, both with a similar central emission wavelength to increase the output power levels.

We present a long-range Brillouin optical time domain reflectometer (BOTDR) based on photon

counting technology. We demonstrate experimentally the ability to perform a distributed temperature measurement, by detecting a hot spot in a thermal bath at 100 km, and the possibility to achieve measurement until 120 km with a spatial resolution of 10 m. We use the slope of a fiber Bragg grating (FBG) as a frequency discriminator, to convert count rate variation into a frequency shift. A performance study of our distributed sensor as a function of spatial resolution is also presented.

The aluminum nitride bandgap energy matches that of the salt-water binding energy. Here we study the effect of 405-nm light on the rates of evaporation when solutions are imbibed within a porous ceramic aluminum nitride wick. Sensitive measurements are taken in a self-referencing setup and compared to the light-induced capillary fluid response. Evaporation rates increase with light illumination when the solution is more saline, which indicates charge-transfer characteristics. Our results show consistent trends and potential for photonic environmental applications in salt-water separation processes.

The Terahertz region electromagnetic spectrum offers significant importance for space observations, including the ability to penetrate dust clouds and atmosphere of planets, as well as detect the unique spectral signatures of various molecules and atoms. Thus, terahertz spectrometers are of significant importance in space observations. However, current terahertz spectrometers face several challenges that limit their performance and application. The key problems include low resolution and sensitivity, limited bandwidth, large volume, and complexity. In this paper, we introduce the concept for a compact terahertz spectrometer that incorporates a metasurface. We start by modelling, designing, and fabricating the metasurface sample, aiming to optimize its performance within bandwidth from 1.7 to 2.5 THz. Next, we utilize a Quantum Cascade Laser that operates at 2.1 THz to validate our concept. Finally, we apply the spectrum inversion method to achieve a high resolution with R (f/Δf) 273. Our results showcase the successful demonstration of a compact and high-resolution terahertz spectrometer. Our findings provide a valuable strategy for spectrometer design, which can be widely applied optics field, particularly in space detection.

In this talk, I will consider optical comb sources characterised by a certain bandwidth, comb line power and background noise level, and discuss requirements to such combs in order to qualify as sources in coherent optical communication systems. I will describe how, that for comb line powers and performances already achievable by integrated micro-ring resonators, a single comb source could act as a highly scalable multi-wavelength (WDM)-source for multi-Pbit/s spatially multiplexed (SDM) systems. I will discuss the possibilities of using a single comb source to support 10s Pbit/s data transmission, and how the scaling to capacities beyond that, is promising. I will discuss using a single comb source for ultra-long-haul transmission systems, such as trans-oceanic reaches of e.g. 8.000 km, and I will show how a comb source performs just as well as a bank of individual lasers, with the added benefit of the possibility to reduce the spectral guard-band, thus increasing the spectral efficiency.

Optical microresonators are attractive comb sources due to their small form factor and stable broad optical spectra. We report on the first demonstration of microcomb-based digital holography. The large line spacing of microcombs promises an unprecedented combination of precision, fast update rate and ambiguity ranges on the scale of a few mm. Using a pulse-driven lithium niobate microcomb of 100 GHz line spacing and a scanning Michelson interferometer, we generate spectral hypercubes of holograms. Our first experimental results show that the amplitude and phase information of the object can be recovered for more than 100 comb lines.

Self-injection locking to a photonic crystal ring-microresonator with synthetic back-reflection is demonstrated for the first time. The on-chip system permits deterministic generation of exclusively single-soliton microcombs and does not rely on random backscattering from defects or imperfections.

In this work, we present a theoretical and numerical study about the generation of double- frequency-comb-like source with Gain Through Filtering (GTF) in passive Polarization Maintaining (PM) fibre ring cavity.

GTF is a nonlinear phenomenon which allows the formation of MI sidebands whose frequencies position is dependant by the central frequency of a spectral filter. By exploiting a PM fibre Bragg grating, and its double central frequency nature, we are able to generate a double-frequency-comb like spectrum, i.e, a spectra on each polarization with a spectral separation equals to the separation of the filter's components.

A phase-modulated frequency-shifting loop is injected by a single-frequency laser at 1.5 µm. In so-called Talbot conditions, i.e., when the modulation frequency is an integer multiple of the inverse of the cavity round-trip time, the loop generates a frequency comb whose temporal trace consists in a train of pulse doublets whose positions in time depend on the frequency of the injection laser. When the modulation frequency is slightly detuned from the Talbot condition, nonlinear frequency chirps are predicted and observed in the output pulse train. We demonstrate that these nonlinear chirps are not restricted to sinusoidal shapes, and also that the loop can be stabilized by exploiting the intracavity phase modulation.

We present the experimental demonstration of the integration of group IV and III/V quantum well and quantum dot structures to silicon nitride, the co-integration of phase change materials on silicon nitride and post fabrication trimming capability of silicon nitride structures.

In this paper, we present controllable and efficient supercontinuum generation with multiple dispersive waves exploiting the quasi-phase-matching (QPM) condition in Si3N4 waveguide. The frequency component needed by QPM condition is introduced by varying the width of the waveguide through propagation. We demonstrated that integrated photonics is an ideal platform to apply QPM strategy, offering new opportunities to tailor the dispersive wave.

Inductively coupled plasma chemical vapor deposition was used to obtain thin films of silicon-rich silicon nitride with a refractive index of 2.44 at optical telecommunications wavelength. The resulting layer was patterned into a 1.6 μm wide waveguide and tested for its nonlinear behavior using a 90-fs all-fiber laser centered at 1630 nm. A significant spectral broadening is demonstrated with a supercontinuum generation from 1300 nm to 1985 nm. Simulations are in fair agreement with the experiments, assuming a nonlinear index of 2 x 10-18 m2/W.

Microresonator solitons enable high repetition-rate optical frequency combs. Their spectral span

scales inversely with the strength of the resonator’s anomalous group velocity dispersion. In a thick (800 nm) silicon nitride platform, wide resonator waveguides (>2 µm) with weak anomalous dispersion are especially promising for the generation of broadband spectra. As wider waveguides have a weaker evanescent field, the coupling strength to their bus waveguide is reduced. To address this challenge, alternative coupler designs, such as pulley couplers are required. Here, we investigate pulley couplers for wide waveguide specifically targeted at broadband soliton generation. We observe significant improvement of the coupling ideality compared to conventional coupler geometries and broadband four-wave mixing spectra are observed in 2.8 µm wide

microresonators.

We present designs and experiments of single-etched amorphous silicon (α-Si) surface grating couplers on a silicon nitride (SiN) waveguide, operating at the telecom (C-band) and datacom (O-band) wavebands. SiN-only grating couplers demonstrate experimental coupling loss of -3.9 dB at 1.55 μm wavelength with a 1-dB bandwidth of 37 nm. Utilizing the hybrid α-Si/SiN platform with subwavelength grating structure, we obtain improved coupling performances, with the optimized fiber-chip coupling loss of -2.0 dB and a 1-dB spectral bandwidth of 42 nm centered at 1.31 μm.

We review here our recent work in achieving mid-infrared (MIR) fibre lasing beyond 5 microns wavelength in Ce3+-doped selenide-chalcogenide fibre, as well as the observed photoluminescence in samples of the same composition but in particulate and bulk glass form as well as unstructured fibre and in the SIF (step index fibre) in which fibre lasing took place.

The passive Q-switching performance of an in-band pumped Dy-doped fluorozirconate fibre laser emitting around 3.1 um is investigated. Passively Q-switched laser operation is demonstrated employing semiconductor saturable absorber mirrors. Stable operation is achieved, with a minimum pulse duration of 464 ns, a highest repetition frequency of 210 kHz and peak pulse powers up to 3 W.

We demonstrate an athermal Brillouin strain sensor using heavily GeO2-doped optical fibers. We also report nonlinear evolution of Brillouin temperature sensitivity as a function of wavelength and strong Brillouin gain in these fibers.

We experimentally demonstrate that simple tapered Ge-Se-Te glass rods with femtosecond pumping enables efficient multi-octave mid-infrared supercontinuum generation, from 1.7 to 16 µm, while keeping an excellent spatial beam profile.

We present the complete (analytical, numerical and experimental) analysis of intermodal-vectorial four-wave mixings proccesses in birefringent fibers. We analyze phase-matching condition and overlap coefficients to indicate possible processes. Then, we demonstrate multiple four-wave mixing processes in LP01 and LP11 modes numerically and experimentally. Finally, we extend theoretical analysis to account higher order modes: LP02 and LP21.

A key component of quantum communication is the distribution of entanglement through networks, however this comes with several challenges. One of the most significant is that direct transmission of quantum information between two nodes via a standard fibre link is unfeasible for transmission distances of more than a few hundred kilometres [1]. A solution is the ‘quantum repeater’ architecture, which distributes entanglement between two nodes via an intermediate repeater node [2]...

We designed a second harmonic generation (SHG) device utilizing the fundamental TE-TM modes to achieve phase matching, and experimentally investigated the relationship between the phase matching wavelength and the waveguide width on the AlGaAs-on-insulator platform. A SHG efficiency of 201% W-1 cm-2 is obtained with a broad bandwidth of 7.6nm in the 1-mm-long waveguide.

We demonstrate experimentally critical coupling for nonlinear conversion in grating-coupled Fabry-Pérot planar microcavities known as Cavity-Resonant Integrated Grating Filters (CRIGFs).

Novel asymmetric designs offer Q-factors from 1000 to 7000 and allow critical coupling with maximised SHG.

We developed an improved coupled-mode model for the linear and non-linear spectral response of CRIGFs which allows accurate insight on the intrinsic and coupling losses in these microcavities.

We designed an X-cut lithium niobate (LiNbO3) membrane dedicated to type I second harmonic generation (SHG) at telecom wavelength. A competitive conversion efficiency compared to a quasi-phase-matched configuration with the advantage of a broadband response of 100nm is shown.

Hybrid photonic devices represent a promising solution to the effective on-chip integration of all the components required for the generation, manipulation and detection of non-classical states of light encoding quantum information. We present an AlGaAs source of highly entangled photon pairs envisioned for the hybridization with silicon-on-insulator integrated platforms, in order to take benefit from the strong second order nonlinearity and the compliance with electrical pumping of the III-V platform and the maturity and CMOS compatibility of silicon photonic circuitry, enabling a wide variety of quantum information applications.

This presentation discusses the recent results on miniaturized pulsed solid-state lasers by utilizing femtosecond-laser inscribed crystalline channel waveguides and carbon-nanomaterial-based saturable absorbers. Based on optical characterization and optimization of the optical materials, integrated compact waveguide lasers present diverse pulsed operation regimes from Q-switching to continuous-wave mode-locking. Pulsing mechanism and various parameters in waveguide lasers are investigated to provide a basis for achieving higher performance of novel on-chip ultrafast lasers.

We present the fabrication of transverse graphitic microelectrodes in a 500 micrometer thick synthetic diamond bulk by means of pulsed Bessel beams. By suitably placing the elongated focal length of the Bessel beam across the entire sample, the graphitic wires grow from the bottom surface up to the top during multiple shot irradiation. The morphology of the microstructures generated and the micro-Raman spectra are studied

as a function of the laser parameters and the diamond crystal orientation. We show the possibility to generate high conductivity microelectrodes, which are crucial for the application of electric fields or current transport/collection in various chips and detectors.

Selective Solar Absorbers (SSAs) are the critical element of high-vacuum flat plate collectors, as these are subject to elevated operating temperatures and thus experience high radiation losses. Here we design and optimize an SSA based on a multilayer design made of HfCx, Si3N4, and SiO2 layers. The structure of the proposed SSA has been optimized to maximize the solar-to-thermal energy conversion efficiency in high vacuum solar thermal panels working at 200 °C, reaching thermal emissivity values much lower than absorbers currently available on the market (<0.02 Vs >0.07) and obtaining unprecedented performances.

Lattice plasmon lasers demonstrated to have many degrees of freedom useful to tailor the lasing properties, as the tuning of the morphological properties of the array or the coupling of proper emitters to band edge states of the plasmonic crystal. Here, we present the results of the study of the lasing emission properties of a hexagonal array of aluminum nanoparticles as a function of the pumping conditions. We demonstrate how the geometrical and dynamic features of the pumping system have a significant impact on the lasing properties without affecting the temporal coherence of the emission. Moreover, by combining different pumping systems and studies at different incidence angles, the relationship between nanoarray, dye and pump has been clarified.

We present PbS colloidal quantum dots (CQDs) as a promising new gain media for the fabrication of tuneable near- to mid-infrared laser sources. Using distributed feedback (DFB) cavities, we have demonstrated lasing within the telecommunication bands between 1.55 μm – 1.65 μm and have now extended this to gain media beyond 2 μm using large PbS CQDs. We have characterised these dots using transient absorption spectroscopy and amplified spontaneous emission, showing them to have a significantly lower gain threshold than their smaller counterparts (down to ~40 μJ/cm2).

Numerous fields of research and industry have undergone revolutionary change because of the unique characteristics of ultrashort laser pulses. Moreover, the ultrafast imaging sensors, such as ICCD technique, can help to understand the ionization features and expansion properties of colliding laser-induced plasma (CLPP) and related stagnation layer (S.L.) geometry. In this work, the effort will be focused on CLPP experiments from two seeds of heterogeneous elements. The research's goal is to analyse the geometrical development of the colliding plasma, the temporal evolution of plume composition features and its associated characteristics. The expansion velocity and forward propagation range (FPR) of the stagnation layer in a nanosecond scale—both of which have been discovered. The ultrafast imaging results give the sight and explain the possibilities of extant technologies that can help to re-engineer the plasma characteristics for the next generation of lithography applications or new selective physical concepts.

Optical security is a promising application of metasurfaces because light has large degrees of freedom in metasurfaces. Although many different structures/materials have been proposed for this purpose, the fabrication of dynamic metasurfaces in a straightforward and scalable manner while maintaining a high security level remains a significant challenge. Herein, a metasurface consisting of a phase-changing Ge2Sb2Te5 (GST) layer and a thin metal back reflector is presented to space-selectively and dynamically control the infrared emission of the surface by a spatially modulated pulsed laser beam. Unlike conventional laser processes using a focused beam, the employed laser printing is an expanded beam-based parallel process that enables the fabrication of wafer-sized emission patterns. Owing to the multispectral responses of GST, mutually independent visible and infrared images can be printed in one region. Grayscale emission patterns can also be obtained by gradually modulating the spatial profile of the laser beam, which makes the replication of laser-printed emission patterns extremely difficult. We also demonstrate that colors images can be obtained by depositing IR lossless layer on the GST surface. All these features indicate that the presented emissive metasurface has the potential for use as an effective platform for anti-counterfeiting

We reported lasing in Er3+ doped tellurite glass whispering gallery mode microspheres fabricated using the plasma torch method.15Na2O25WO360TeO2 doped with 0.5 mol% Er3+ is used for the fabrication of microspheres. Laser light from the pump is coupled to the microsphere through a half and a full tapered fiber. An optical spectrum analyzer receives the counter propagating light from the microsphere. Pump lasers of 980 nm and 1480 nm are used to achieve the laser emission at 1570 nm.

The special attention has been paid to visualization and monitoring of harmful radiation to quantify the radiation intensity and prevent the undesired exposition. For these purposes, so called radioluminescent materials are widely exploited. Special attention has been paid to the research of luminescence optical fibers, which can be used for a construction of distributed optical sensors. We present a versatile nanoparticle doping approach to Zn2+-doped silica optical fibers. Zinc oxide nanoparticles were applied into porous silica frit by a nanoparticle-doping method providing a preform which was drawn into an optical fiber. The maximum concentration of Zn2+ ions in the fiber was 0.78 at. % causing the refractive index reached the value of 1.459. The fiber outer diameter was 124.8m and the fiber core diameter was 14.9 m matching the standard telecommunication dimension. The fibers exhibited a blue radioluminescence showing the emission maximum at 395 nm. The fiber properties make them worthy of investigation as sensing elements of distributed sensors of high energy radiation.

Abstract. Nanoporous metallic systems exhibit a new generation of advanced materials with potential in a wide variety of technological fields among them catalysis, photonics, optoelectronics and sensors. Their high surface-to-volume ratio, multimodal nanoscale moieties, ability to host guest materials, and inhomogeneous surface at the submicron scale distinct them from both bulk metals and conventional plasmonic materials as well as meta-surfaces. Those structures can be prepared through different fabrication and synthesis strategies including chemical dealloying, assembly of pre-synthesized metallic nanoparticles, and via templating. In a sharp contrast with these preparation strategies, we have demonstrated one can fabricate a macroscopic nanopourus metallic networks by using physical vapor deposition in a short single-step process. These materials are highly pure, and they show very unique linear and non-linear optical properties, among them high Second-Harmonic-generation response.

Herein, we will discuss their growth process mechanism, and utilize it for more complex 3d structure which behave as SHG reflectors.

In order to develop an affordable clinical diagnostic instrument for use in more decentralized settings, we have assessed the feasibility to move from hyperspectral to multispectral imaging via parsimonious feature selection. The targeted application is the label-free identification, at the species-level of uropathogens from images of bacterial colonies on their growth support. We show that the number of predictors, i.e. discrete spectral channels, can be dramatically reduced from hundreds to less than 10 channels with limited or no performance loss. The impact of bandwidth is also investigated to take into account the high degree of redundancy of raster images obtained by diffuse reflectance and propose a suitable design for a simple filterwheel based solution. Targeting the 8 most prevalent bacterial species responsible for > 80% of urinary tract infections, up to 94% of correct identification rates was reached using only 4 narrow spectral windows extracted from degraded hyperspectral images.

We analyzed fabrication errors of nonperiodic-multilayer-dielectric gratings that were designed to have a high reflective diffraction efficiency for one wavelength and a high transmittance for another wavelength at the same time. Significant deviations were found between the measured and calculated efficiency values although the groove profile parameters were very closed to the design values. The source of error was attributed to coating errors of the film stack. To explain the deviation well, we estimated the parameters of actual coating stack by reverse calculations and using scanning electron microscope. We recalculated the diffraction efficiencies and the results showed that the actual film stack parameters were inverted well. This provided a foundation for us to reoptimize grating groove parameters on the basis of actual coating stack.

Total internal reflection fluorescence (TIRF) has come of age, but a reliable and easy-to-use tool for calibrating evanescent-wave penetration depths is missing. We provide a test-sample for TIRF and other axial super-resolution microscopies for emitter axial calibration. Our originality is that nanometer(nm) distances along the microscope’s optical axis are color-encoded in the form of a multi-layered multi-colored transparent sandwich. Emitter layers are excited by the same laser but they emit in different colors. Layers are deposited in a controlled manner onto a glass substrate and protected with a non-fluorescent polymer. Decoding the penetration depth of the exciting evanescent field, by spectrally unmixing of multi-colored samples is presented as well. Our slide can serve as a test sample for quantifying TIRF, but also as an axial ruler for nm-axial distance measurements in single-molecule localization microscopies, supercritical-angle fluorescence, and related super-resolution.

To create an affordable clinical test for use in more decentralized settings, we are developing a multispectral imaging system based on a filter wheel and a smartphone. Our application is the label-free identification of uropathogens from images of bacterial colonies directly on a non-chromogenic culture medium. Using feature selection techniques, we have previously shown through calculations, the possibility to move from hyper- to multi- spectral imaging by exploiting less than 8 spectral bands. Here, we confirm our findings by testing a database of true multispectral images acquired using a filter wheel holding up to 22 dichroic bandpass filters with a 10 nm bandwidth. Performance is reported for 5 species using only 6 filters. Probabilistic SVM algorithms were implemented to allow to reject species other than the targeted most prevalent uropathogens as it is crucial to keep the false-positive rate low. Evolution of specificity and sensitivity with probability threshold are discussed in the light of probability frequency distributions.

A longer exposure to blue light has negative effects on organisms, therefore we present an optical assembly based on a hexagonal design with blue LED light for homogeneous irradiation of cultures of Drosophila melanogaster, which has a variability range of illuminance controlled by the change of local current, useful for the evaluation of various factors under this parameter.

We present the characterization results for an analogically addressed vertically aligned liquid crystal on silicon microdisplay (VA-LCoS). We show that it covers more than 360º phase modulation range at 1550 nm, and that in the visible the range available enables the generation of multiorder DOEs. There are basically no studies dealing with the characterization of vertically aligned high resolution LCoS devices, since the ones typically found in the literature and commercially available correspond to the parallel aligned. We have also verified that the microdisplay used in this work is free from flicker, which is a very interesting feature for application where the phase stability is of the utmost importance. The results shown here represent a first step in the work underway oriented to the generation of programmable DOEs for telecommunication applications (C-band) and for the visible spectrum.

Optical frequency combs operating at low repetition rate exhibit high pulse energy for a given average power. Therefore, low repetition rate frequency combs may efficiently drive nonlinear frequency conversion into the mid-infrared or extreme ultraviolet region to extend frequency metrology to such exotic wavelengths. In this work, we have experimentally demonstrated a low-noise optical frequency comb operating at 40 kHz repetition rate using a Yb:KYW mode-locked laser (center wavelength at 1030 nm, repetition rate 40 MHz) and an acousto-optic modulator-based pulse picker. We have stabilized a single comb mode to an ultra-stable continuous wave laser operating at 1033 nm. The integral rms phase noise (in the range 10 Hz - 20 kHz) was measured to be 167.2 mrad.

In recent years, a great scientific effort was dedicated to extending the operating range of lasers and amplifiers beyond the conventional 1.5 – 2.0 μm. Lasers operating in the mid-infrared range 2 – 5 μm find various applications as LIDARs, sensors, medicine, etc. However, the commonly used silica glass is unsuitable for emission above 2 μm due to the high phonon energy of the silica lattice, which completely quenches emission at longer wavelengths. The materials based on crystalline structure are perspective low-phonon materials for laser operation in the mid-infrared rage. In this contribution, we present the preparation and properties of a novel laser-active material based on holmium-doped yttrium-hafniate (Ho0.03Y0.97)2Hf2O7. The emission around 3 μm is successfully demonstrated.

This experimental work describes our work on spectrometric measurements (spectral responses) and measurement of sensitivity of solar radiation by (simulating the solar to a powered lamp) on commercial light emitting diodes of different colors (LEDs). The first experiment was carried out at the electronics department in University of USTHB Bab Ezzouar (Laboratory of thin layers) which has a measurement bench allowing the relative spectral representation of the photo of the detector noted Vphot (λ).

In addition, at ENS Kouba in the LSIC laboratory, a second work has also allowed us to set up a device which measures the sensitivity of different LEDs radiated by the lamp as a function of illumination power of a light source in using a luxmeter according to the voltage across the light emitting diodes (LEDs).

32-channel arrayed waveguide grating spectrometer (AWG) at 1800 nm is demonstrated on a 2-μm-thick silicon-on-Insulator (SOI) platform. The design and simulation of the device are performed using the beam propagation method (BPM) and we obtain the 3-dB channel width, channel spacing, and extinction ratio of 1.16 nm, 1.56 nm, and 5.17 dB, respectively. The AWG demultiplexer can be applied in the central part of a spectrometer which is replacing in integrated optics a prism or a grating in conventional free-space optics

Deformed microdisc cavities possess versatile application potential ranging from microlasers to sensors. Here, we investigate arrays of several coupled microcavity resonators. The coupling interaction between the cavities induces a wide range of features that sensitively depend on, and therefore can be controlled via, the intercavity distance. We use semiclassical methods from mesoscopic optics to characterise the system and its dynamics in real and phase space using Husimi functions. Our findings can inspire novel optical devices such as supersensors or novel light sources.

Analog photonic techniques can perform better than conventional digital electronics, which have significant limitations when it comes to processing fast RF signals on the fly. We show that a simple photonic architecture, based on a bi-directional frequency-shifting loop, makes it possible to calculate in real time the cross-correlation function of two broadband signals for about 200 values of their delay simultaneously. Additionally, our architecture also enables to perform spectral analysis of signals with 16 GHz instantaneous bandwidth, 100 % probability of interception, and detection electronics below 10 MSa/s.

Metamaterials are artificial media designed to display properies going beyond those of ordinary materials. Particularly interesting are ε-near-zero (ENZ) media with real part of the permittivity going to zero in a certain spectral range. Examples of ENZ metamaterials are metal dielectric multilayers, which allow to tune the position of the ENZ wavelength depending on their composition and which have been found to have enhanced Kerr-type nonlinearities, i.e. nonlinear absorption and nonlinear refraction. In this work we define a figure of merit for the design of multilayer metamaterials with strong Kerr-type nonlinearities and compare our predictions with both simulations and experimental results.

The study of liquid crystal (LC) director distribution is an important area of research in materials science and technology. Parallel-aligned liquid crystal (PA-LC) devices have been extensively studied due to their applications in liquid crystal displays, optical devices, and sensors. Estimating the LC director distribution is a critical step in designing and optimising PA-LC devices. This work shows the results derived from applying novel optimisation techniques to estimate the liquid crystal (LC) director distribution in parallel-aligned liquid crystal (PA-LC) devices. Moreover, the genetic algorithm (GA) has been applied and compared with the minimisation of the Frank-Oseen free energy through the Euler-Lagrange equations. The GA is a stochastic optimisation technique that can effectively explore the search space and find the global optimum. Overall, this study's results demonstrate the GA's effectiveness in estimating the LC director distribution in PA-LC devices. This approach can improve the performance and design of liquid crystal displays, optical devices, and sensors. Furthermore, it can be extended to other fields where the optimisation of complex systems is required. Further research is needed to optimise the GA parameters and to explore its potential in other applications.

This work proposes a sensor that utilizes a transmission scheme for measuring glucose aqueous solutions based on surface plasmon resonance. A comparison between the performance of two sensors with similar lengths and different diameters is performed. The first sensor comprises a multimode optical fiber with a diameter of 400 μm and a 10 mm middle section of the cladding removed. The second sensor is similar, except that the fiber has a diameter of 600 μm. The sensors were evaluated for their performance in measuring glucose concentrations ranging from 0.0001 to 0.5000 g/mL. The 400 μm sensor demonstrated high sensitivity however, the sensor with a diameter of 600 μm attained a slightly higher maximum sensitivity of 322.0 nm/(g/mL).

The refractometric analysis of ethanol-water mixtures is hampered because this type of binary solution does not present a linear behaviour. In this work it is proposed a multimode Graded-Index Fiber (GIF) tip sensor for the measurement of ethanol in binary liquid solutions of ethanol-water. The probe is fabricated by fusion-splicing a 500 µm GIF to a Single Mode Fiber (SMF) and it operates as a refractometric sensor in reflection. Samples of ethanol-water mixtures were measured at different temperatures (20°C to 60°C) to evaluate the probe's capability to detect variations in ethanol refractive index. The samples have different % (v/v) of ethanol, in a range between 0% and 100%.

White Light Interferometry, known for its absolute measurement capability and high precision, had its greatest scientific impact towards the end of the 20th century. In this work, it was assembled and characterized a fibre Mach-Zehnder interferometer (MZI) as an interrogator and a fibre Fabry-Perot interferometer (FPI) as a displacement sensor. A measurement bandwidth between 65 μm and 95 μm was obtained for FPI cavities close to 2.35 mm, at sampling frequencies between 600 Hz and 1500 Hz. Additionally, a resonant frequency at 550 Hz was achieved, allowing for an interrogation band higher than 135 μm. It was also determined a minimum absolute resolution of ± 66 nm, corresponding to a relative resolution of ± 9.4×10-4 in relation to the total band.

The existence of new highly thermally and chemically stable active optical materials is a challenging task for current photonics research targeted on high-power lasers. Holmium-doped titanates crystallizing in the pyrochlore lattice, represent a promising class of materials. However, their high processing temperature limits their applications in integrated optical devices. This weakness can be overcome by laser assisted processing as an alternative to common heat-treatment. The amorphous thin films were prepared by a sol-gel method followed by a dip-coating process and densified in a rapid thermal annealing furnace. The densified films were annealed by a CO2 laser beam. The laser irradiation induced a crystallization process resulting in the formation of nanocrystalline (Ho0.05Y0.95)Ti2O7. The prepared film of a thickness 576 nm exhibited an optical transmission of 91.66% close to the maximum theoretical limit of a silica substrate. The film's refractive index at 632 nm was 2.219. The formation of the nanocrystals caused the activation of the electronic transition 5I75I8 at 2 m and the emission bands showed the distinct Starks splitting which is characteristic for (Ho0.05Y0.95)Ti2O7 phosphors. The presented approach can be used to prepare transparent luminescence films as an alternative method to common heat-treatment processes.

High harmonic generation (HHG) is one of the richest processes in strong-field physics. It allows to up-convert laser light from the infrared domain into the extreme-ultraviolet or even soft x-rays, that can be synthesized into laser pulses as short as tens of attoseconds. The exact simulation of such highly nonlinear and non-perturbative process requires to couple the laser-driven wavepacket dynamics given by the three-dimensional time-dependent Schrödinger equation (3D-TDSE) with the Maxwell equations to account for macroscopic propagation. Such calculations are extremely demanding, well beyond the state-of-the-art computational capabilities, and approximations, such as the strong field approximation, need to be used. In this work we show that the use of machine learning, in particular deep neural networks, allows to simulate macroscopic HHG within the 3D-TDSE, revealing hidden signatures in the attosecond pulse emission that are neglected in the standard approximations. Our HHG method assisted by artificial intelligence is particularly suited to simulate the generation of soft x-ray structured attosecond pulses.

In order to accomplish more functional and efficient light routing on a chip, photonic integration is necessary. Particularly in quantum technologies, which require a high precision of operation, avoiding bulky optical arrangements is in high demand. Scalable and robust photonic components open up a plethora of possibilities. The light guiding systems have to be able to cover a wide range of operational wavelengths and different light polarization states. In this work, we present the first numerical results for our approach of a PIC producing NIR circularly polarized light based on a Si3N4 material platform. This concept includes waveguides and metasurfaces that are easily integrable on the chip surface of many trapped-ion quantum computer architectures.

In a nonlinear optical waveguide with defocusing Kerr-type nonlinearity, we discuss the existence of a type of stationary nonlinear waves with propagation-invariant density profiles, consisting of vortices located at the vertices of a regular polygon with or without an anti-vortex at its center.These polygons rotate around the center of the system and we provide approximate expressions for their angular velocity. We have computed the evolution of the vortex structures and discuss their stability and the fate of the instabilities that can unravel the regular polygon configurations. Such instabilities can be driven by the instability of the vortices themselves, by vortex-antivortex annihilation or by the eventual breaking of the symmetry due to the motion of the vortices.

Tb3+-doped single-crystalline Gd3Ga5O12 layers are grown by Liquid Phase Epitaxy on (111)-oriented undoped substrates, and their structure, composition, morphology and photo- and radioluminescence are studied. Layers doped with 6 at.% Tb3+ with a thickness up to 20 μm appear promising for single crystal film scintillators with a sub-μm spatial resolution and waveguide lasers as they exhibit good quality, uniform distribution of Tb3+ ions, optimized light output (~50% of that for Ce:YAG), weak concentration quenching of luminescence and low afterglow for a 15 bit dynamic range.

We present an experimental realization of a novel layered metamaterial we label enhanced

epsilon-near-zero (eENZ). The structure is a stack of alternating thin films made of ENZ– and dielectric

material and it can be designed for desired refractive/reflective properties by appropriately tuning the film

thicknesses. The structure supports thin film resonances, guided modes and Ferrel-Berreman plasmon modes

and the performance of the structure shows a large improvement to many currently available bulk ENZ

materials. Additionally, we recently demonstrated the possible use of eENZ for coherence switching in lasers

[1]. We demonstrate the design, fabrication and characterization of the optical properties of the eENZ stack

and compare the measured transmission properties with transfer matrix method (TMM) simulations.

Erbium-doped lasers and amplifiers exhibit emission around 1.5 μm, which makes them perspective in various applications, such as telecommunications, material processing or defence. The conventionally used silica glass suffers from various drawbacks, such as low solubility of erbium ions or high phonon energy of the silica lattice, which limit the luminescence properties. The zinc-silicate glass-ceramics containing ZnO or Zn2SiO4 nanocrystals represent a suitable alternative. The incorporation of erbium ions into the nanocrystals should result in the enhancement of luminescence properties. In this work, we prepared a zinc-silicate glass-ceramic material containing Zn2SiO4 nanocrystals by the controlled heat treatment of a precursor glass. The luminescence properties of the 1.5 μm emission were measured and the influence of the crystallization on the near-infrared emission was evaluated.

We present a monolithic Yb-doped fiber laser system delivering 200 W average power of femtosecond pulses at tunable GHz repetition rates. The system is based on a GHz electro-optic (EO) frequency comb operating in the nonlinear regime. The EO comb pulses at 1 µm wavelength are initially pre-compressed to sub-2 ps, amplified to 2.5 W, and finally boosted to 200 W in a newly designed large-mode-area, Yb-doped photonic crystal fiber. Continuously tunable across 1-18 GHz, the picosecond pulses experience nonlinear propagation in the booster amplifier, leading to output pulses compressible down to several hundreds of femtoseconds. To push our system deeper into the nonlinear amplification regime, the pulse repetition rate is further reduced to 2 GHz, enabling significant spectral broadening at 200 W. Characterization reveals sub-200 fs duration after compression. The present EO-comb seeded nonlinear amplification system opens a new route to the development of high-power, tunable GHz-repetition-rate, femtosecond fiber lasers.

Among the different fundamental aspects that govern the design and development of elongated multimaterial structures via the preform-to-fiber technique, material association methodologies hold a crucial role. They greatly impact the number, complexity and possible combinations of functions that can be integrated within single fibers, thus defining their applicability. In this work, co-drawing strategies to produce monofilament microfibers from unique glass-polymer associations are discussed.

We experimentally demonstrate the synchronization of regularly vibrating soliton molecules by means of an injected modulated signal. Such synchronization is analyzed in real time through the sensitive balanced optical correlation technique. We also unveil the existence of chaotic intra-molecular vibrations, to which we successfully apply a similar control strategy. These findings strengthen the hypothesis of internal dynamics of soliton molecules essentially ruled by a reduced number of degrees of freedom, allowing applicative prospects.

In this work, an optical fiber flowmeter based on a Michelson interferometer is presented. The Michelson interferometer uses a long period fiber grating (LPFG) to couple light to the cladding modes followed by a section of a GO-coated single mode fiber (SMF). By radiating the GO thin film, it will increase its temperature changing the effective refractive index of the optical cavity of the Michelson interferometer. By placing the sensor on a gas flow, its temperature surface will decrease in a proportional manner to the flow rate. The sensor was studied in both static and dynamic dry nitrogen flow, attaining an absolute sensitivity of 17.4 ± 0.8 pm/(L.min-1) and a maximum response time of 1.1 ± 0.4 s.

The aim of this study was to use wavefront sensing to objectively evaluate the effects of vision therapy in subjects with insufficiency (AI) and infacility of accommodation (AINF). Aberrometry was performed with a Shack-Hartmann wavefront aberrometer for different accommodative stimuli in one subject with AI and one with AINF before and after treatment with vision therapy (VT). A control subject received a placebo treatment. Real-time accommodative response, accommodation and disaccommodation reaction time, accommodative microfluctuations and root mean square of higher order aberrations were compared before and after VT/placebo. VT was effective and wavefront sensing can be used to detect AI and AINF and evaluate these subjects during VT.

The purpose of this study was to use real-time wavefront aberrometry to detect accommodative excess (AE) and to analyse the optical quality of the eye in subjects with this dysfunction. AE was detected from the accommodative response obtained by real-time wavefront aberrometry. These subjects had a significant accommodative lead to all stimuli and had difficulty relaxing accommodation. The root mean square (RMS) of high order aberrations (HOA) was higher in subjects with AE for lower stimulus and for disaccommodation than in the control group. However, the subjects with AE showed a decrease in the RMS of HOA with an increase in accommodative response. Primary spherical aberration tended to become more negative with accommodation in both subjects and there was no difference between the groups. Real-time wavefront aberrometry can be used as an objective method to detect accommodative excess.

Enhancement of quantum dot (QD) fluorescence in a hybrid system of a porous silicon microcavity (pSiMC) and silver nanoplatelets (AgNPs) has been estimated using numerical simulation. The system was simulated as a periodic unit cell made of a pSiMC with a resonant wavelength peak at 605 nm, an AgNP with a resonance at 604 nm and a quantum dot (QD) with an emission peak at 605 nm. For comparison, simulations were performed for an AgNP and a QD in a reference single-layered system with a high refractive index. The QD fluorescence was enhanced in the AgNP/pSiMC hybrid system, mainly due to the higher excitation rate.

CBC (Coherent Beam Combining) is a key technology for the realisation of intense lasers. In this context, PISTIL (PISton and TILt interferometry), a precise metrology tool for measuring segmented wave surfaces, has been developed and used in particular to characterise and diagnose CBC ultrafast and digital laser in the framework of the XCAN (X Coherent Amplification Network) project at the École Polytechnique. We propose here to use it in a way to help the optimisation of control techniques by including PISTIL in an XCAN type CBC laser simulator. This will allow an easy tuning of the control laws, outside the clean rooms in which these large lasers are deployed and without the need to start them up.

We investigate coherent Kerr combs generation via Brillouin lasing in a non-reciprocal cavity. This approach offers adjustable repetition rates and enhanced coherence. A numerical model is presented that accounts for the interplay between Brillouin scattering, Kerr effect, and cavity resonant feedback. Through quantitative agreement with experiments, our study highlights the importance of mode-pulling effects in setting the comb’s dynamics, which had been overlooked inprevious fiber experiments. Finally, we discuss limitations and suggest scaling laws for these systems.

We demonstrate that coupled waveguides systems can be operated in the so called non-adiabatic

regime. In this regime, light can undergo transitions between different steady states in a manner analogue to the transition of an electron between energy levels. This approach contrasts with the previous concepts in integrated photonics that rely exclusively on the adiabatic control of the flow of light. We show in particular that abrupt changes of the control parameters are not required to create such non-adiabatic transitions. The constraint for adiabaticity being lifted, light can now be manipulated optimally. And the analogy between the time evolution of a quantum system and the propagation of light in a waveguides array can be pushed one step further.

We numerically investigate dispersive and nonlinear properties of step-index tellurite fibers from detailed measurements of refractive indices for two tellurite-glass systems employed in fiber manufacturing. In particular, two typical step-index configurations are analyzed, namely weak and strong index differences between core and cladding glasses. We reveal that a wide range of dispersion-shifted features for tellurite fibers can be obtained in the 2 –3 μm range, and we show the potential application of such dispersion-engineered fibers for nonlinear wavelength converters between near- and mid-infrared regions.

In this work, we investigate the nonlinear phenomenon of self-attraction of light state-of-polarization in optical fibers by means of dual-Omnipolarizers. More precisely, we compare the performance in terms of polarization attraction efficiency of two different systems: The first configuration relies on a series of two successive Omnipolarizers, whereas the second system includes an imbricated Omnipolarizer into the feedback loop of the main device. Our study reveals that for the same budget of power, the cascading of two Omnipolarizers allows to improve the performance of the polarization attraction phenomenon, leading to an output degree-of-polarization close to unity for any arbitrary polarized input signal.

Understanding the ultrafast processes at their natural-time scale is crucial for controlling and manipulating nanoscale optoelectronic devices under light-matter interaction. In this study, we demonstrate that ultrafast plasmon resonances, attributed to the phenomenon of Extraordinary Optical Transmission (EOT), can be significantly modified by tuning the spectral and temporal properties of the ultrashort light pulse. In this scheme, all-optical active tuning governs spatial and temporal enhancement of plasmon oscillations in the EOT system without device customization. We analyze the spectral and temporal evolution of the system analytically through coupled harmonic oscillator model and discuss time-resolved spectral and spatial dynamics of plasmon modes through 3D-FDTD simulation method and wavelet transform. Our results show that optical tuning of oscillation time, intensity, and spectral properties of propagating and localized plasmon modes yields a 3-fold enhancement in the EOT signal. The active tuning of the EOT sensor through ultrashort light pulses pave the way for the development of on-chip photonic devices employing high-resolution imaging and sensing of abundant atomic and molecular systems.

In this work, we report on an all-optical, real-time, nonlinear temporal compression technique based on a counter-propagating degenerate four-wave mixing interaction in birefringent optical fibres. As a proof-of-concept, we demonstrate the extreme temporal focusing and interleaving of a 10-Mbit/s data packet into a 10-Gbit/s data sequence, with record temporal compression factors ranging from 3 to 4 orders of magnitude and including non-trivial on-demand time-reversal capabilities. Our approach is scalable to different photonic platforms and offers great promise for ultrafast arbitrary optical waveform generation and related applications, while enabling the compression of THz-bandwidth optical signals from low-cost, low-bandwidth optical waveform generators.

The "cavity dumped" laser architecture is a very efficient solution for having a high-efficiency pulsed laser source with a shorter pulse duration than a classic Q-Switch laser architecture. This solution makes it possible to obtain laser beams of almost constant pulse duration independently of the repetition rate and the pumping rate and to obtain very good conversion efficiency at 2w and 3w. Unfortunately, this architecture suffers from a handicap with a duration of the transient regime that can exceed ten milliseconds. The very long duration of this transient state makes this architecture incompatible with inherently transient applications such as marking or laser micro-machining. We propose here an electro-optical solution to decorrelate the transient state specific to the CD architecture and that of introduced by the application.

We propose a theoretical method to model the complex phenomenon of oscillating ultrashort pulse pair molecules. Using a phenomenological viewpoint, we construct effective dynamical systems, whose degrees of freedom are the inter-pulse timing and overall phase. The effective dynamical system is characterized by a limit cycle attractor that is fit to the experimentally measured soliton oscillation using data-driven methods. Good agreement is achieved between the dynamical system orbits and experimental observations made in a mode-locked fiber laser.

This contribution presents a method for producing nanoscale color pixels for high-resolution displays using 3D printing of vertically freestanding nanostructures containing red, green, or blue light-emitting quantum dots (QDs). Traditional methods for producing pixels suffer from decreased brightness and pixel density at higher densities due to the reduced volume, but our 3D printing method allows for individual control of brightness by adjusting pixel height in 3D, resulting in a two-fold increase in brightness without changing lateral dimensions. We demonstrate sub-micrometer pixels representing primary colors at a super-high density, enabling image patterns with a pixel resolution of 8,400 ppi and individual modulation of sub-pixels with a possible pixel resolution of 5,600 ppi in triangular-delta and Bayer type designs. The method can be applied to displays, information storage, cryptography, and image sensors. The 3D printing method is a versatile approach for photonic research and has potential for contributing to the development of a range of applications.

We propose an experimental method for the generation of coherent terahertz radiation in the spectral region between 0.2 THz and 2 THz, with a high repetition rate of nearly 100 MHz, and with an average power at the milliwatt level. An Ytterbium-doped mode locking laser is amplified to 60 W, and pulses are stacked into an optical cavity up to 750 W. There, they interact with a Gallium Phosphide crystal producing THz radiation via optical rectification. With the cavity enhanced configuration, we show that more than one order of magnitude can be gained with respect to simply focalize the 60 W beam into the GaP crystal.

A general technique for obtaining the soliton number, and hence the nonlinear coefficient, in waveguides with high dispersion and loss is derived and demonstrated numerically and experimentally in a kilometer-long standard silica fiber pumped close to 2 µm.

We discuss a new proof of the non-locality of single-photons using a concrete physical observable such as the local energy density. As an illustration of this non-locality, we compute the mean value of the local energy observable for the spontaneous emission from a Hydrogen atom. We find that, in the subspace of single-photon states, the mean value of the local energy density observable is non-zero everywhere and decreases as a power of the distance.

Broadband Coherent anti-Stokes Raman Scattering (BCARS) enables the whole vibrational spectrum of cytologically prepared samples to be obtained using a hyperspectral raster scan approach. This technique has the potential to enable high-throughput automated detection of cell abnormalities. Images are distorted by the non-resonant background which requires a treatment for proper analysis. Using statistical denoising and phase retrieval returns Raman spectra similar to that of a spontaneous Raman measurement. Here, we present our work using this method for single-cell imaging of PEO1 ovarian adenocarcinoma cells prepared with the ThinPrep processor which enables label-free Raman cytology.

Broadband Coherent anti-Stokes Raman Scattering (BCARS) microscopy is a useful technique for chemical analysis and allows the full vibrational fingerprint spectrum of a specimen to be obtained in milliseconds. A major drawback to this technique is the presence of the non-resonant background response producing interference which prevents classical spectral analysis of the sample. Using a convolutional autoencoder and measurements of the laser characteristics, we have shown that it is possible to remove this background without requiring supervision, as is typically required for conventional removal methods. This approach therefore simplifies the analysis of hyperspectral images obtained with BCARS.

We report on modular implementation of digital holography that we recently proposed. The module is designed such that it may be added to an existing brightfield microscope's image port for digital holographic microscopy functionality. The proposed system is modular, portable, and cost-effective and not require path-length realignment when changing samples. The square in-line Mach-Zender architecture is used and the off-axis condition is achieved using two sets of wedge prism pairs; this approach offers advantages over other Mach-Zender nearly common-path modules, particularly in path length matching of object and reference wavefields for low-temporal coherence sources. Additionally, the proposed system allows for continuous variation of the tilt angles of the object and reference wavefields incident on the sensor, making it readily adaptable to any microscope and camera.

We report on a polarization-resolved spectroscopic study of Sm3+-doped monoclinic KGd(WO4)2

crystals. The transition probabilities for Sm3+ ions were calculated using a modified Judd-Ofelt theory. For the 4G5/2 → 6H9/2 transition in the red spectral range, the stimulated-emission cross-section is 5.59×10-21 cm² at 649.0 nm (for light polarization E || Np) and the luminescence lifetime of the 4G5/2 state is 719 μs (0.4 at.% Sm3+-doping). Sm:KGd(WO4)2 is promising for orange and red lasers.

Excitability in dynamical systems refers to the ability to transition from a resting stationary state to a spiking state when a parameter is varied. It is the mechanism behind spike generation in neurons. Optical non-linear resonators can be excitable systems, but they usually present a fast response compared to neuronal systems, and they prove difficult to observe experimentally. We propose investigating optical resonators with delayed Kerr effects, specifically in two different geometries: an oil-filled single-mode cavity with thermo-optical nonlinearity, and two coupled, symmetrically driven cavities. When the Kerr effect is delayed, even a single cavity exhibits excitability. However, we show that it suffers from limitations on the thermo-optical relaxation time in order to be realized experimentally. We overcome these limitations using the geometry with coupled cavities, where the thermo-optical relaxation time acts as a memory. This slow variable enables to tailor the spiking frequency and it mimics neuronal behaviours by enabling large-period spiking.

We report on our recently developed method for tracing lines of flux in three-dimensional diffracted wavefields using an approach we call ‘non-linear ray tracing’ but which can be more accurately described as tracing the lines of flux in the context of the Eikonal function. These ‘rays’ navigate through the diffracted field guided by the derivative of the phase at a sequence of successive points. Our approach is based on the Angular Spectrum method, a numerical algorithm that accurately and efficiently calculates diffracted fields for numerical apertures <0.7. This is used to generate a three-dimensional grid of complex wavefield samples in the focal region, followed by tracing the flux through this volume. The ray propagates in a straight line between two consecutive planes within the volume; the phase derivative is calculated at each plane to direct the ray on the next step of its journey. We demonstrate the effectiveness of our approach by generating results for focused laser beams with TEM00 and TEM01 laser profiles. We also simulate the effects of optical aberrations, described by Zernike polynomials, on the three-dimensional focused wavefield. Our non-linear ray tracing method provides a powerful and efficient approach for tracing lines of flux through complex three-dimensional wavefields, offering an exciting new tool for understanding these complex systems.

Convolutional layers are a critical feature of modern neural networks and require significant computational resources. In response, optical accelerators have been developed as a low-energy, high-bandwidth approach for performing large-scale convolutions. We extend these methods to act on many input channels each with their own set of convolutional kernels. We simulate the performance of this system with ray-tracing and evaluate its performance.

Abstract. Samples of H6TPPS J aggregates and bundles, deposited on glass and aligned under nitrogen flow, were measured in a 2-photon microscopy setup. Changes in the polarization state of the incoming laser have shown a difference in the resulting 2-photon scanning of the same measured sample, revelling otherwise hidden features. In addition, tracing the response of certain areas under different polarisation can provide information about the arrangement of the dipoles in that area. This shows the significant role of polarisation in 2-photon measurement, and the need to consider such effects in the microscopy of biological samples.

Certain amorphous dielectric materials can prevent the propagation of electromagnetic waves within a certain frequency range, i.e., they exhibit a photonic band gap where the density of state is zero. Materials of this kind are promising for fundamental physics and numerous technological applications. Little has been known about how waves penetrate such material, are reflected, and propagate through the material near but outside the bandgap. In a recent paper, our group proposed a solution to this problem, where we also consider the occurrence of Anderson localization of light [1]. Here we present experimental results on light transmission and reflection in amorphous self-uniform dielectric networks [2] made with direct laser writing. We compare the experimental data with the model.

[1] Scheffold, F., Haberko, J., Magkiriadou, S., & Froufe-Pérez, L. S. (2022). Transport through Amorphous Photonic Materials with Localization and Bandgap Regimes. Phys. Rev. Lett., 129, 157402. doi:10.1103/PhysRevLett.129.157402

[2] Sellers, S.R., Man, W., Sahba, S. and Florescu, M., 2017. Local self-uniformity in photonic networks. Nature communications, 8(1), p.14439.

In this paper, we have demonstrated the beam steering experiments with the help of our optical phased array devices. The lateral beam steering has been showed successfully with the wavelength through the tunable laser source. The number of output channels were 512 and the array width was kept more than a millimeter with a 2-µm pitch. The beam steering angle has been measured as 45° and the beam movement was 1°/nm. As the chip does not collimate the beam vertically, so, a commercial collimating lens has been used in the vertical direction.

We are developing and characterizing an EUV/soft X-ray sensitive sCMOS-sensor based detector suitable for high repetition rate imaging and spectroscopy as well as single photon detection experiments

This study explores the quantum properties and fluorescence properties of optically trapped nanodiamonds (NDs) with nitrogen-vacancy (NV) centers. We focus on T1-relaxometry measurements and fluorescence-spectra under varying green laser powers, while considering the IR laser's influence. The study also optimizes laser sequences for efficient NDs trapping within cells, ensuring minimized effects on fluorescence and T1 properties. With NDs' unique photostability, biocompatibility, and sensitivity to magnetic fields, our findings suggest new modalities for biophotonics applications such as cellular imaging or sensing, pushing forward the rapidly evolving field.

We design a photon pair source with emission at 606 nm and 3.98 MHz linewidth, which matches the spectral properties of praseodymium ions. To reduce the linewidth the use of cavity-enhanced spontaneous four-wave mixing was proposed. The designed integrated source is suitable for praseodymium quantum memories.

We demonstrate how to measure scattering spectra of single plasmonic nanoparticles using a confocal darkfield setup. We give an overview of considerations and problems we encountered when employing a darkfield technique based on filtering illumination under low angles instead of the conventional high-angle filtering by darkfield objectives.

Mid-infrared supercontinuum sources are particularly important for identifying and characterizing molecules and materials through spectroscopy, thus enabling key applications. We here demonstrate the possibility of combining both mid-IR supercontinuum generation and evanescent wave spectroscopy in a single chalcogenide fiber device by means of heat-and-draw processes to manage linear and nonlinear wave-guiding properties.

We investigated infrared reflectivity of undoped and Tungsten (W) doped Vanadium dioxide (VO2) films at varying temperatures. Undoped VO2 exhibited a clear phase transition at 100°C, achieving near 0% reflectivity, or perfect light absorption. As W doping concentration increased, the phase-transition temperature decreased, maintaining the zero-reflectivity condition. Only a 0.75% W doping enabled room temperature perfect absorption without heating the film.

A number of experiments confirm the appearance of longitudinal components of the electric or magnetic field in parts of the space of the optical beam. The aim of this paper is to show that this local appearance is not spatially confined, and can propagate to infinity in the form of structured beams. The polarization distribution in the paraxial space of the beam can be explained using a model of a polarization field that arises behind an infinite axicon. The electric field oscillates in a local position along a 3D ellipse and can create a wave in space. The orientation of the ellipse and its ellipticity depend on the position. Analytical solutions are shown to describe the polarization of the electric and magnetic fields behind the axicon, which satisfy the wave equation for different polarization states of the input beam such as radial, azimuthal, linear, and circular. This infinite axicon model example can be extended to describe paraxial structured beams of finite size but infinite distance propagation range. These beams have been generated using optical elements with huge optical aberrations and experimental results, demonstrating some of the beam properties, are presented.

We theoretically study the interaction between two parametrically driven solitons in a doubly resonant optical parametric oscillator with non-negligible Kerr nonlinearity. We show that two solitons can interact through the depletion of the pump in the presence of a high walk-off between signal and pump, leading to the formation of bound states.

We performed infrared optical characterization of polycrystalline β-Ga2O3 films, in the 10-18 μm range, deposited by metal organic chemical vapor deposition on sapphire substrates. Our results show that it is possible to obtain a dominant β-phase film, with a well-defined, normal to surface z-axis orientation. These results are confirmed by reflection spectra performed at 45° incidence angle which reveals a z-phonon Reststrahlen band as a function of the incident field linear polarization.

In this work, we investigate a microscopic model for a quantum electromagnetic field interacting with a linear nonmagnetic metallic medium. We obtain the diagonal form of the Hamiltonian of the model and find the exact values of the creation-annihilation coefficients. Using these results, we compare the decay rate of an atom located near the metallic one-dimensional slab with the results in the literature.

Frequency comb lasers with fast gain recovery times naturally favor the emission of frequency modulated periodic signals, which are useful for multiple applications in spectroscopy and communications. Models and phase measurements predict an ultrashort strong intensity spike at the instantaneous frequency discontinuity of the cavity cycle.

Here we experimentally study the ultrashort spike of fast-gain frequency modulated combs through direct upconversion sampling, and measure a width below that of a transform-limited pulse. Specifically, we demonstrate a mid-infrared quantum cascade laser which inherently lases in a frequency modulated comb and produces a spike with full-width at half-maximum below 600 fs, which is below the Fourier-limit derived from the corresponding spectrum. We believe these ultrashort spikes can be highly beneficial for sub-bandwidth time domain measurements. Using mean-field theory based simulations, we confirm the occurrence of such features as well as further optimize our system for going even further below the Fourier-limit.

Optical vortices have found a wide range of applications thanks to their helical phase topology allowing to carry the orbital angular momentum. In this work, self-interfering vortex beams are utilized in a new single-shot holographic method for the circular phase retardation measurement. The vortices carrying information about the phase retardation introduced between two orthogonal circular polarization modes are generated by the spin to orbital angular momentum conversion. The phase retardation is stored in off-axis holographic records acquired in a common-path setup using a geometric-phase grating. In the proposed method, the circular phase retardation is reconstructed in the Fourier domain, surpassing the measurement precision provided by methods restoring the retardation from the rotation of a Double-Helix Point Spread Function (DH PSF). The developed method can be adapted for application to polarimetry, orientation imaging and diagnostics of nano-emitters.

We present a surface emitting THz quantum cascade laser frequency comb with an adjustable chromatic dispersion compensation via a mechanically tunable GTI cavity. Surface emission and high optical feedback into the laser cavity are achieved by a planarized ridge waveguide design with low reflectivity facets and two broadband patch array antennas for coupling to an external mirror (back side) and for power extraction (front side). We demonstrate direct and reproducible manipulation of the frequency comb state, specifically the comb stability and beatnote frequency tuning, by controlling the position of an external movable mirror.

In the present work, the viability of a novel recording geometry to produce reflection holographic couplers has been analyzed. Recalling the idea of previous works, photopolymers are used as the recording material, as they are well-suited for the intended see-through application. Moreover, Kogelnik’s theory fundamentals give us the proper background to examine the proposed design, where no prisms or microlenses arrays are used. Aiming to support the analysis, we provide experimental evidence that the produced gratings exhibit the correct properties to work as a coupler.

We study the lateral leakage of a silicon nitride loaded lithium niobate on sapphire waveguide in the mid-infrared regime. We then combine lateral leakage and dispersion engineering to numerically demonstrate mid-infrared supercontinuum generation extending from 2400nm to 5000nm

Disspative Kerr Solitons are generated in an integrated standing wave Fabry-Pérot microresonator. Enabled by synthetic anomalous dispersion provided by a pair of Photonic Crystal Reflectors (PCR) forming a high-Q cavity, the generated soliton pulses exhibit a unique spectral profile extending beyond the PCRs’ bandgap.

Since the development of the first fibroscope in the late nineteenth century, the use of innovating glass fibers has opened promising perspectives for medical applications particularly in the domain of multimodal imagery[1]. In this work, tellurite glasses have been used to design step-index optical fibers with a rectangular core-section for supercontinuum generation in the near infrared domain. The tellurite glasses selection and the fibers manufacturing by the stack-and-draw process will be presented. Characterizations performed on bulk samples and fibers will also be detailed[2]. The spectral broadening, which is obtained in this work in a short fiber sample, is used for imaging mouse kidney cells, labelled with three different fluorochromes, by means of two and three-photon absorption. Despite the multimode nature of the output beam, clear images of tubules, actin and nucleus are collected with a spatial resolution down to 1.2 µm[3].

This work demonstrates SiN strip-loaded lithium niobate waveguides with nonlinear optical properties, focusing on their performance when pumped at telecom wavelength. Experimental results show second and third harmonic generation in periodically poled SiN/LiNbO3. Furthermore, simulations reveal that these waveguides can be dispersion engineered to generate supercontinuum. The findings highlight the potential of SiN strip-loaded lithium niobate platform in sustaining broadband nonlinear light sources.

We performed the design and fabrication of polymer waveguide circuits, aiming for applications as electro-optic devices. Uniform waveguides with over one centimeter of length were fabricated by soft nanoimprint lithography. These multimode waveguides present a height of 3 µm and low surface roughness (2 nm), with a thin residual layer of 600 nm. Propagation losses at 1550 nm are estimated to be around 7 dB/cm.

In this work, we make a step forward in the manipulation of light on the surface of one-dimensional photonic crystal through Bloch Surface Waves (BSW) within resonant structures of various types. Linear Fabry-Perot cavities eventually combined with diffraction gratings allow to directly couple BSW from free-space radiation. Design, fabrication and experimental characterization are provided.

Line-shape measurements of the fundamental vibrational band of CO at 4.6 µm perturbed by N2 with a mid-infrared frequency comb-based Fourier-transform spectrometer were performed. Precise collisional line-shape parameters for 41 lines were determined, including the pressure broadening and shifting and speed-dependence of the collisional width. The results were compared with sparse literature data available.

Here, we present the preparation of composites with green persistent luminescence using melting process. The composites are phosphate glass (75NaPO3-25CaF2 and 90NaPO3-10NaF (in mol%)) with embedded phosphors: CaWO4: Yb3+, Tm3+ crystals with blue upconversion and SrAl2O4:Eu2+,Dy3+ with green persistent luminescence. Green persistent luminescence above 0.3 mcd/m2 can be seen for ~ 30 minutes after charging with 980 nm due to energy transfer between the blue upconverter crystals and the persistent luminescent phosphors. Challenges related to the fabrication of such composites are discussed.

This research introduces a novel and highly efficient method to interconnect two metallic nanostrips that support the propagation of surface plasmon polariton (SPP) waves exploiting a photorefractive soliton guide. The intricate design of the multilayer geometry enables light control diffraction at the metallic nanostrip's end and reduces its angular dispersion. Moreover, the system's on/off state can be switched by exploiting the epsilon near zero properties of the indium tin oxide (ITO) layer. The photorefractive crystal positioned between the two plasmonic waveguides enables the self-confinement of light, generating a waveguide that can be utilized by both the writing light and other wavelengths transmitted as signals. The resulting SPP waves can be efficiently recoupled in the second nanostrip, with an efficiency of around 40% across a broad range of wavelengths. This cutting-edge approach paves the way for significant advancements in the field of nanophotonics and provides a fundamental framework for the development of new, highly efficient optical interconnects in nanoscale systems. The findings of this study have implications for a wide range of applications, including nanoscale sensing, optical computing, and data communication.

Electrons have been invaluable in the development of tools to study nanoscale phenomena. In this talk we explore novel avenues to explore light-matter coupling at the nanoscale by leveraging electrons, made accessible through recent technical advancements. On the one hand, advances in nanofabrication allow the manufacturing of electrically driven nanogap antennas. By placing an excitonic material on top of the gap, hybrid light-matter states are formed. We demonstrate how the electrically controlled tunneling-electron-current can be used as a source to drive the polaritonic modes. This has direct applications to the development of on-chip nanophotonic quantum devices. On the other hand, recent advances in controlling the quantum properties of collimated free-electron beams have positioned them as promising probes for investigating quantum matter at the nanoscale. We provide a model Hamiltonian that captures the interplay between electronic transitions and optical modes. Our Hamiltonian is constructed using macroscopic Quantum Electrodynamics (QED) principles and is parameterized using the electromagnetic Dyadic Green's function. We apply this model to study state preparation on an isolated quantum-emitter (QE), and to perform polariton sensing with modulated free electrons in a hybrid QE-optical cavity setup.

We report the preliminary experimental results for an amorphous silicon carbide (a-SiC) thermo-optic phase shifter (TOPS). This device is based on microring resonator (MRR) structure with a titanium (Ti) heater placed on the top of the device, separated by 1.5 μm thick SiO2 to reduce the optical loss. The proposed a-SiC microring has a thickness and a radius of 1.1 μm and 33 μm, respectively. By applying an electrical power in the Ti heater, a resonance wavelength shift at an optical wavelength of λ=1550 nm is shown, and the extracted thermal tunability is 52.2 pm/mW.

Silicon carbide (SiC) on insulator has emerged as a powerful platform for integrated nonlinear optics owing to its broad transparency window, its high refractive index and its large second- and third-order optical non-linearity and propagation loss as low as 0.1 dB/cm . Here we investigate the formation of visible and mid-IR dispersive waves in SiC waveguides. Owing to the strong optical nonlinearity of SiC, pulse energies as low as 200 pJ are sufficient to generate a broad spectrum centered in the 3-4 µm range, region of the fundamental CH, NH, OH stretches in molecules. Low seeding powers open up the prospect of fully on-chip devices including ultrashort-pulse seed source and broadening waveguides and even of integrated spectrometers for trace gas sensing.

We numerically demonstrate an advanced digital signal processing method for compensating the

phase-to-amplitude distortion conversion caused by the interaction of the phase noise induced by pump dithering with the dispersive fibre channel in fibr

In many conventional optical manufacturing processes, lapping is still a standard method to provide

polishable surfaces. With the increasing use of CNC technology, efforts are being made to substitute the

lapping process in the process chain. The paper presents studies that compare the lapping and fine grinding

processes and provide an assessment of the subsequent polishing process. By using fine grinding with resin

bond tools, polishing times can be significantly reduced and subsurface damage structures minimized. Ultrafine grinding is also an important shaping process for the production of complex surface geometries, such as

free-form optics.

To sustain cellular functions, a cell needs to transport a variety of cargos within the complex intracellular milieu. This task is mainly carried out by molecular motors that move along filament tracks. Despite the grand challenges to fully understand how cells exactly manage to execute all their intelligent functions, construction of artificial nanosystems by taking inspiration from the working principles that cellular components follow, is undoubtedly an intellectually efficient approach.

In this talk, we will show several types of bio-inspired optical nanosystems, which can perform rotation, twisting, or swinging motions enabled by dynamic DNA nanotechnology. Our approach outlines a general scheme to build dynamic plasmonic nanoarchitectures, in which multiple optical elements can be readily reconfigured or transported to designated locations over long distances, resulting in programmed structural changes with high fidelity. Such plasmonic structures can find useful applications in different fields, ranging from optical sensing to data storage. In particular, the possibility to translocate optical elements in multiple configurations can be used to explore new approaches to encode information at high density.

Ultrafast, intense, laser pulses are able to induce a wealth of non-linear effects in the atmosphere as they propagate, such as filamentation, plasma generation, non-linear photochemistry and shock waves. The successful use of these processes for guiding natural lightning strikes and for piercing clear channels in fog for free space optical communication (FSO) is presented.

We present the latest progress towards high resolution, long range Coherent Focal Plane Array sensors based on FMCW ranging with an emphasis on monostatic architectures.

Optical correlations are useful for many sensing and metrology applications including imaging, interferometry and LiDAR. Quantum illumination (QI) is a special example: it uses non-classical optical correlation (entanglement) to effectively filter uncorrelated noise from real LiDAR signals. Despite its impact QI only excels in the few photon regime. Therefore, when built using inherently low power quantum sources QI cannot compete with classical LiDAR systems with mW level probe light. In this talk we demonstrate quantum-inspired LiDAR which utilizes broadband phase correlations in nonlinear waveguides with effective second order nonlinearities, to effectively reduce in-band noise power by over 100dB with single-photon sensitivity. It is empowered by a receiver which utilizes sum-frequency in optical waveguides with record conversion efficiency.

Rapid, reliable and low cost techniques to fabricate biosensors is a hot topic nowadays. Here, we present a BIO-grating fabricated by means of local, selective denaturing of molecules using UV radiation. A phase-mask is used to generate an interferometric pattern of 1420 nm pitch that, when illuminating a biolayer of BSA molecules lead to its periodic deactivation. After the biorecognition of the specific antibody, aBSA, a BIO-grating is generated due to the height difference between the protein, and the complex protein + antibody. We present the optimization of the fabrication of the BIO- gratings and their AFM characterization. Also, the biosensor performance in terms of limit of detection and limit of quantification will be presented.

The development or the improvement of production processes are necessary aspects, in order to enhance the quality and efficiency in optical manufacturing. This paper presents an approach to manufacture fine grinding tools in a very flexible and efficient way. A new filament composed of polyamide, ZrO2 particles and diamond grains is developed and used in an additive manufacturing process for tool fabrication. The resulting tools are successfully applied in an ultra-fine grinding process on fused silica samples.

We report experimental results of a frequency shifted digital holography setup for spatially resolved vibrometry. A spatially homogeneous artificial phase modulation is used as a reference to correct for speckle noise. Furthermore, when superimposed upon the object vibration with slightly different frequency, the resulting beat can be evaluated. The beat frequency is invariant under relative motion between the object and interferometer, providing robustness in presence of parasitic low frequency vibrations. In addition, the ‘working point’ is raised out of the noise floor, providing the opportunity to enhance the sensitivity at small vibration displacements. The method is demonstrated by measurements on a vibrating clarinet reed.

Long-chain hydrocarbons, petroleum and diesel, have long been used as source of energy for locomotives. Unlike it’s short-chain counterpart petroleum, diesel fuel is considered dirtier due to black soot particulates it emits that poses greater health hazard. Here, we attempt to measure the absorbance spectra of premium diesel fuels, neat and adulterated, using terahertz (THz) frequency domain spectroscopy to determine the level of impurities that can further exacerbate its emission. Two broad absorption peaks at 6.42 THz and 7.75 THz as well as narrow peaks at 13.07 THz, 13.88 THz, and in the range of 16-17 THz, characterized the premium diesel. These spectral features are well identifiable in the adulterated samples but their intensities vary depending on the type of impurities. Decrease in the absorbance is observed with water contaminant, increase in isopropanol, while sulfur and methanol contaminants did not influence the absorbance spectra. This technique demonstrates initial but promising results in probing adulteration in petrochemical products.

Stable isotopic compositions of carbon and oxygen (δ13C et δ18O) measured from carbonates are used in geology to reconstruct paleotemperatures and to learn about the evolution of the biogeochemical carbon cycle. The standard technique used since the middle of the XXth century to measure isotopic ratios is based on a wet chemical protocol which CO2 is evolved from the acidic dissolution of carbonates followed by quantification of CO2 molecules isotopologues using mass spectrometer or infrared spectroscopy. This is a lengthy protocol that necessitate to manipulate acid solution and numerous gas phases purification steps before isotopic measurements. Our new preparation technique aims at offering an alternative to the wet chemical preparation of the samples by using a direct extraction of CO2 via a laser-induced calcination process. In addition to save time, this method allows to consider spatially resolved and automated in-situ measurements and does not necessitate further purification steps of the evolved CO2 during calcination.

New Ytterbium based femtosecond lasers system are very interesting systems due to their high repetition rate / average power, compactness and long term stability due to direct diode pumping. Associated with nonlinear compression schemes (multipass cell or capillary), few cycle pulses are now available at around 1 µm. This presentation will present our recent work in this field and the extension of these sources in the mid-infrared by using intrapulse difference frequency generation and amplification to cover the 4 – 20 µm spectral range with high conversion efficiency. An optimization of the polarization state and chirp of the input pulses and a temporal synchronization leads to sub-two optical cycles CEP stable pulses at 8 µm with hundreds of mW average power (> µJ energy per pulses at 250 kHz).

The complicated electric field structure of ultrashort pulses as characterized by frequency-resolved optical gating (FROG) algorithms often results in local convergence, which does not accurately represent the actual field pulse. We present an efficient and universal test procedure applicable to any FROG retrieval algorithm that allows recognition of the erroneous local convergence. The 100% efficacy of the procedure is demonstrated using Line-Search FROG algorithm, and comparison is given with the performance of a standard extended ptychographic iterative FROG trace retrieval engine.

The generation of sub-five optical cycle pulses centered at 11.2 µm wavelength with 50 µJ energy at a 1 kHz repetition rate is reported. A GaSe optical parametric chirped pulse amplifier (OPCPA) is driven by the residual 2.0 µm pump and 5 µm idler of a high-energy midwave-IR OPCPA. The latter serves as driver for hard X-ray generation and this makes the achieved fs longwave-IR pulses available for X-ray pump-probe experiments.

Artificial intelligence (AI) is a potentially disruptive tool for physics and science in general. One crucial question is how this technology can contribute at a conceptual level to help acquire new scientific understanding or inspire new surprising ideas. I will talk about how AI can be used as an artificial muse in quantum physics, which suggests surprising and unconventional ideas and techniques that the human scientist can interpret, understand and generalize to its fullest potential.

[1] Krenn, Kottmann, Tischler, Aspuru-Guzik, Conceptual understanding through efficient automated design of quantum optical experiments. Physical Review X 11(3), 031044 (2021).

[2] Krenn, Pollice, Guo, Aldeghi, Cervera-Lierta, Friederich, Gomes, Häse, Jinich, Nigam, Yao, Aspuru-Guzik, On scientific understanding with artificial intelligence. Nature Reviews Physics 4, 761–769 (2022).

[3] Krenn, Zeilinger, Predicting research trends with semantic and neural networks with an application in quantum physics. PNAS 117(4), 1910-1916 (2020).

We report the first application of the Machine Learning technique of data-driven dominant balance to optical fiber noise-driven Modulation Instability, with the aim to automatically identify local regions of dispersive and nonlinear interactions governing the dynamics. We first consider the analytical solutions of Nonlinear Schrödinger Equation – solitons on finite background – where it is shown that dominant balance distinguishes two particularly different dynamical regimes: one where the nonlinear process is dominating the dispersive propagation, and one where nonlinearity and second order dispersion act together driving the localization of breathers. By means of numerical simulations, we then analyse the spatio-temporal dynamics of noise-driven Modulation Instability and demonstrate that data-driven dominant balance can successfully identify the associated dominating physical regimes even within the turbulent dynamics.

Long-term forecasting of extreme events such as oceanic rogue waves, heat waves, floods, earthquakes, has always been a challenge due to their highly complex dynamics. Recently, machine learning methods have been used for model-free forecasting of physical systems. In this work, we investigated the ability of these methods to forecast the emergence of extreme events in a spatiotemporal chaotic passive ring cavity by detecting the precursors of high intensity pulses. To this end, we have implemented supervised sequence (precursors) to sequence (pulses) machine learning algorithms, corresponding to a local forecasting of when and where extreme events will appear.

The amount of transverse orbital angular momentum (OAM) carried by the spatiotemporal

optical vortices (STOVs) is being hotly debated. In this contribution I unveil the mystery of the amount of total, intrinsic and extrinsic transverse OAM carried by STOVs. They do not carry any total transverse OAM about a static transverse axis crossing the STOV center. Yet, STOVs carry a transverse OAM about a moving transverse axis crossing the STOV center permanently, which is identified with the intrinsic OAM, and an opposite extrinsic transverse OAM about the fixed axis. These results raise questions about the interpretation of second-harmonic and high-harmonic experiments or simulations with STOVs, and the capability of STOVs to transmit OAM to particles. Other advances such as observation of vortex splitting and topological charge flipping of high-order STOVs in free space and in dispersive media, and the transverse torque exerted by optical elements will be discussed.

Moving from diffractive optics to metalenses, novel tools for structuring light are provided for the integration in compact optical layouts. Here we propose new metaoptics designed for light shaping into structured beams implementing on-demand vectorial configurations. Different optical layouts are achieved in order to generate orbital angular momentum (OAM) vector beams with different shape and peculiarities.

Airy wave packets constitute a very peculiar type of structured light: during their propagation, their transverse profile undergoes a self-accelerating displacement while it remains shape invariant. They are thus the only non-dispersive beam-type solution to the Helmholtz paraxial equation in free space. Such properties are possible by virtue of their infinite power content. However, experimentally, Airy beams can only be reproduced in an approximate manner, with a limited extension and hence a finite power content. To this end, different cutoff procedures have been reported in the literature, based on a convenient tuning of the transmission properties of aperture functions. In this Communication, we present and discuss our latest advances in the analysis of the effects that convolving an Airy beam with different aperture functions have on their propagation properties. More specifically, we make use of a trajectory-based methodology, which allows us to analyze and explain the beam propagation in terms of trajectories directly connected with the beam local phase variations.

Highly anisotropic crystals have recently attracted considerable attention due to their ability to support polaritons with unique properties, such as hyperbolic dispersion, negative phase velocity, or extreme confinement. In particular, the biaxial van der Waals semiconductor α-phase molybdenum trioxide (α-MoO3) has received much attention [1] due to its ability to support in-plane hyperbolic phonon polaritons (PhPs) —infrared (IR) light coupled to lattice vibrations in polar materials— with ultra-low losses, offering an unprecedented platform for controlling the flow of energy at the nanoscale.

In this talk, we will show experimental demonstrations of the unique behavior of PhPs in these crystals, including the visualization of anomalous cases of the fundamental optical phenomena of refraction [2] and reflection [3], and the exotic phenomenon of canalization, in which PhPs propagate along a single direction with ultralow losses [4].

In this work, we experimentally demonstrate the photo-inscription of complex waveguiding structures by a single diffracting Bessel beam (BB) propagating in a biased SBN crystal. Our optical platform enables all-optical control of the characteristics of such induced configurations by tailoring the parameters such as beam size, the electric field, and the input beam intensity. Our numerical results are in good agreement with our experimental work. In addition, we numerically study the interaction of two counterpropagating (CP) BBs under nonlinear conditions and the spatiotemporal dynamics of these photo-induced configurations. These results suggest more opportunities for fully controllable complex waveguiding structures and new all-optical solutions for active components in optical communication.

Spin-orbit interactions (SOI), describing the transfer of a spin degree of freedom to an orbital angular momentum (OAM), have been widely explored in recent opto-acoustic studies for applications mainly in spintronics and for topological insulators. We report the observation of SOI by Brillouin scattering in an optical nanofiber. Specifically, we describe the transfer of a spin degree of freedom from light incident to the nanofiber to an acoustic vortex with a topological charge of order 2 in the form of OAM. Coupled with the phase matching condition for the energy conservation during Brillouin scattering, it results in a backscattered wave with a spin opposite to the incident wave. This observation allows considering applications of opto-acoustic Brillouin memory based on polarization conversion through a SOI.

We report on the use of PMMA/DR1 coating to enhance the efficiency of photon pair generation in silica nanofibers. The coating improves the second-order nonlinear susceptibility of the nanofibers, leading to improved photon pair generation efficiency. We investigate the effect of varying the nonlinear optical properties of the composite material, and we characterize the photon pair generation efficiency of the coated silica nanofibers. Our modelling results show a significant enhancement in photon pair generation efficiency by a factor of 1000 compared to a bare silica nanofiber.

Quantum technologies require advanced optical metamaterials whose properties can be tailored and controlled as desired. Hyperbolic metamaterials have great potential for applications in nonlinear nanophotonics, such as all-optical switching, optical limiting, mode-locking and optical sensing. In this work, we show how to obtain strong third-order optical nonlinearities in hyperbolic multilayers exploiting the effect of bulk plasmon polaritons. We demonstrate the tunability of these properties with angle and polarization, and we propose a model to predict them. We evidence the enhancement of the nonlinear response in low-loss metamaterials.

We report that Ca3TaAl3Si2O14 is a positive uniaxial crystal and provides second-order frequency conversion. Indeed, we performed direct measurements of phase-matching conditions for second-harmonic generation and sum-frequency generation up to 3.5 µm. The simultaneous fitting of recorded data provided the Sellmeier equations of the two principal refractive indices and the magnitude of the nonlinear coefficient.

We report a new and more precise Sellmeier equation derived using the quasi-phase-matching curves obtained from the study of the optical parametric generation (OPG) in 1D periodically poled LiTaO3 (1D-PPLT) of different periods at low and high pump power

Photon energy upconversion, i.e. the conversion of several low-energy photons to a photon of higher energy, offers significant potential for nano-optoelectronics and nanophotonics applications. The primary challenge is to achieve high upconversion efficiency and a broad device performance range, enabling effective upconversion even at low excitation power. This study demonstrates that core/shell semiconductor nanowire heterostructures can exhibit upconversion efficiencies exceeding what was previously reported for semiconductor nanostructures even at a low excitation power of 100 mW/cm2, by a two-photon absorption process through conduction band states of the narrow-bandgap nanowire shell region. By engineering the electric-field distribution of the excitation light inside the NWs, upconversion efficiency can be further improved by eight times. This work showcases the effectiveness of the proposed approach in achieving efficient photon upconversion using core/shell NW heterostructures, resulting in some of the highest upconversion efficiencies reported in semiconductor nanostructures. Additionally, it offers design guidelines for enhancing energy upconversion efficiency.

We built and studied a singly resonant optical parametric oscillator using a 5%MgO:PPLN partial cylinder pumped by a sub-nanosecond microlaser emitting 1064 nm at a repetition rate of 1kHz. It is continuously tunable from 1410 nm up to 4330 nm by rotating the cylinder and a total energy of several micro Joules is emitted with a beam quality factor M² lower than 3.