Conference Agenda

The development of modern spintronics materials require novel characterization tools capable of characterizing nanometer-sized spin textures. Neutrons are a convenient probe for this task due to their angstrom-sized wavelengths, electric neutrality and robustly controllable spin state. Recent research has focused on enabling access to new degrees of freedom in order to provide a neutron toolbox capable of characterizing emerging materials. This includes the development of holographic and tomographic techniques for characterizing the 3D bulk spin textures and the techniques for creating structured neutron beams with helical and skyrmion-like spin-orbit states. Here we provide a concise overview of this work and discuss future prospects and applications.

By combining the concepts of structured light and quantum interference, we design and experimentally demonstrate a simple and robust scheme that tailors quantum interference to engineer photonic states with spatially structured coalescence along the transverse profile. To achieve this, we locally tune distinguishability of a photon pair by spatially structuring the polarisation and creating a structured quantum eraser.

Nonlocality in quantum systems is fundamental for secure remote quantum information tasks and tests of fundamental quantum physics. While loophole-free nonlocality verification has been achieved with polarization-entangled photon pairs, extending this to other degrees of freedom remains challenging. Here, we demonstrate detection loophole-free quantum steering utilizing optical vector vortex states, which are formed by combining orbital angular momentum (OAM) and polarization. This advancement goes beyond traditional polarization encoding, opening avenues for secure quantum communication devices and device-independent protocols in free-space and satellite-based scenarios.

Encoding information in time-bin entangled photonic systems enables the implementation of quantum technologies that are compatible with both integrated and fiber frameworks. Extending such an encoding to high-dimensional (qudit) time-bin entanglement provides a tool towards scaling the information capacity, noise resilience, and scalability of information processing. Here, we demonstrate scalable time-bin entangled qudits in a programmable photonic chip, as well as in a fully fibered coupled loop system.

A variety of applications requires light and infrared radiation to be shaped and controlled actively. In our laboratory we are working on shaping light using silicon photonics on a chip and in free space using metasurfaces. Key to these applications are materials that can be tuned or switched optically, electrically or thermally. In this presentation I will give an overview of cutting edge developments in shaping of light using phase change materials. I will also address efforts at modelling these effects using new techniques from the toolbox of deep learning neural networks.

We show that, by exploiting the optical memory effect, it is possible to track a moving object through a strongly scattering layer, despite its image being obscured to us.

Here we propose to exploit the natural instability of thin solid films, i.e. solid state dewetting, to form regular patterns of monocrystalline atomically smooth Si, Si1-xGex and Ge nanostructures that cannot be realized with conventional methods. Additionally, the solid-state dewetting dynamics is guided by prepatterning the sample by a combination of electron-beam lithography and reactive-ion etching, obtaining precise control over number, size, shape, and relative position of the final structures. Methods and structures will be optimized towards their exploitation mainly in photonic devices application (e.g. anti-reflection coatings, colour-filters, random lasers, quantum emitters and photonic sensors).

Spin-orbit coupling in nanoscale optical fields induces the formation of a spin momentum component transverse to the orbital momentum. Herein, we firstly explore the manipulation of dynamics by the spin-orbit effect on gold monomers, observing how the self-induced spin from localized resonance results in trajectory shifts controlled by the incident polarization. Secondly, we discuss the spin-orbit behavior in systems of gold dimers that due to field hybridization effects within the gap exhibit changes in the nontrivial spin momentum that lead to the formation of a vortex and anti-vortex spin angular momentum (SAM) pair on the opposite surfaces of the nanoparticles. The results could offer advantages for biological and aerospace fields, leading to the development of new systems and applications in the field of spin-optics.

Photonic band gap crystals are being pursued for their ability to control emission and vacuum fluctuations radically. Here, we examine the spontaneous emission of lead sulfide quantum dot nanocrystals within 3D photonic band gap crystals. These crystals, formed by etching deep pores in a silicon bar from two directions, possess a diamond-like inverse-woodpile structure, with quantum dots infiltrated into the pores using a toluene suspension. At frequencies just above the band gap, we observe >18x more intensity from quantum dots inside the crystal than the same number of dots outside, indicative of strongly enhanced emission. Time-correlated single photon counting shows fast non-exponential decay, reflecting the varied local densities of states of different quantum dots within the nanopores. We employ a log-normal model to interpret properties of the time-resolved decay at different emission frequencies and observe that the most frequently occurring decay rate is up to a factor 10x greater in the photonic crystal than outside. Current efforts focus on enhancing signal-to-background and signal-to-noise ratio, essential for probing inhibited decay within the band gap, and further studies on 3D band gap cavity superlattices and quasicrystals.

Optical tweezers are designed to trap nano- and micro-scale particles. Once trapped, it is possible to move the particles but this requires complex mechanical adjustments to the optical system. In this paper, an easier way to trap and move multiple particles simultaneously is proposed, that uses a digital mirror-array and freeform micro-lens-array to generate several steerable optical traps inside a light-field.

The first practical step in resolving the turbulence issue in satellite-to-earth laser communications has been the use of conventional adaptive optics systems. The concept of a modal iterative approach is presented in this study, which combines some of the characteristics of the indirect methods outlined. This allows for a significant decrease in the loop bandwidth consumption throughout the iterative process. With the assumption that each speckle may be Fourier linked to a plane wave mode in the pupil plane, this approach employs the individual speckles of a single short-exposure intensity image. The approach is described, together with the general mathematical background. In the end, this work presents a numerical analysis of the approach performance estimate in a turbulent satellite downlink scenario.

At PTB, a multi camera measurement setup is developed for the traceable determination of the modulation transfer function (MTF) of objectives. In recent works the MTF of a reference objective is determined within the image field in an angular range of up to ±20° to the optical axis. For the investigation of angular dependency of the transfer function the MTF for a given spatial frequency is evaluated at a datum point. A common choice of the datum point is the focus point P_f.

There are different methods to obtain the focus point from the measurement data. In this contribution several approaches for the determination of the focus point are investigated and compared. In addition, owing to the temperature depending extension of the measurement setup the position of the focus point strongly depends on the ambient temperature. We present also some results of the investigations on the influence of temperature changes on the position of the focus point.

The FAMU (Fisica degli Atomi MUonici) collaboration aims to measure the proton Zemach radius through muonic hydrogen (µp) spectroscopy. The experimental setup relies on a custom-developed pulsed mid-IR laser source that can be tuned over a specific 6780-6790 nm wavelength range needed to ignite the hyperfine transition of the µp ground state 1S (also known as spin-flip transition). The excitation is observed as a distinctive muonic X-rays emission resulting from the oxygen impurity present in the hydrogen target. The mid-IR emission is produced by Difference Frequency Generation (DFG) in a non-linear crystal, pumped with a fixed wavelength 1064 nm Nd-YAG laser and a tuneable Cr:forsterite laser centred on 1262 nm. This setup produces more than 1.2 mJ at 6780 nm with a linewidth smaller than 30 pm. The experiment requires the laser to run continuously 24/7 in a restricted/radiation-controlled area and for this reason a specifically developed control software permits to remotely act on the laser. The characterization of a series of different non-linear crystals was performed during the development of the laser, resulting in the choice of BaGa4Se7.

Here we present a new light-responsive composite showing reversible anisotropic stretching in response to green laser irradiation with varying polarization. The elongation/compression parameters and the residual strain after deformation reversal are evaluated by means of a Fourier-based analysis, which exploits a periodic 2D pattern imprinted onto the surface. Two illustrative examples of macroscopic actuation driven by light polarization are demonstrated.

Graphene constitutes a broadband energy acceptor, avoiding labeling, photobleaching and complicated photophysics. Graphene quenches fluorescence of fluorophores in a range of 0-40 nm, following a d-4 distance dependence. Due to Graphane Energy Transfer (GET) a single dye molecule shows a reduced fluorescence intensity and a shortened fluorescence lifetime as a function of its distance to graphene. This information can be used to determine the position of the dye molecule to graphene and to sensitively report on distance changes in real-time. In our first realization, we used DNA origami nanopositioners to place a fluorophore and other molecular components at a defined distance from graphene. With this approach, using single-molecule fluorescence microscopy techniques and several different assays we demonstrated among others: switching dynamics of a DNA pointer between two binding sites with high time resolution, dynamics of a flexible DNA tether influenced by viscosity or target binding, 3D superresolution imaging with isotropic nanoscale resolution, a biosensing assay with single DNA molecule detection in a novel unquenching assay format. Our recently developed tools to connect DNA and graphene enable single base-pair resolution. We use this approach to visualize structural properties of DNA which precede direct interactions with biomolecules and DNA-protein interactions.

Molecular beacons (MBs) represent a powered tool for the detection of RNAs, such as micro-RNA (miRNA) and messenger RNA (mRNA), which play an important role as indicators of the progress of different pathologies in the human body, from the chronic ones to cancer. Two examples are provided here of how the combination of molecular beacons with detection platforms based on surface enhanced Raman scattering (SERS) can lead to the realization of more performing and reliable biosensors. The first case concerns the use of a MB, engineered for specific detection of a miRNA associated with chronic obstructive pulmonary disease. Silver nanowires were used as SERS substrate on which the MBs are immobilized. A femtomolar detection limit has been reached. The second approach is based on soda-lime glass microrods on which silver nanoparticles were grown using the ion-exchange technique followed by an appropriate thermal annealing post-process. Production parameters were optimized aiming at exposing the embedded silver nanoparticles on the surface of the microrods. By functionalizing these nanoparticles with a MB specific for the mRNA for survivin, the microrods were successfully tested for SERS and fluorescence effects, allowing the detection of the complementary sequence.

In this study, we present an innovative optical biosensor designed for the precise detection of

Interleukin-6 (IL-6), a crucial cytokine associated with various pathological conditions. Our biosensor is

based on silicon porous material meticulously modified with a molecularly imprinted polymer (MIP),

ensuring specific and sensitive recognition of IL-6 molecules. Fabrication process involves the

electrochemical etching of silicon porous chips followed by the electrodeposition of MIP, tailored to

selectively bind IL-6 targets. Through rigorous testing across a range of IL-6 concentrations, our sensor

exhibits remarkable sensitivity, showcasing discernible optical responses proportional to the varying analyte

concentrations. Furthermore, we assessed the sensor's performance using bovine serum, a complex biological

matrix, to simulate real-world sample conditions. Encouragingly, the sensor maintains its selectivity and

optical response in the presence of serum components, affirming its robustness and applicability in practical

diagnostic settings.

A set of protein biomarkers are largely recognized as responsible of neurodegeneration mechanisms and hence as potential targets to be detected in low abundant concentrations in body fluids for performing early diagnosis. As an example, the Tau protein experiences a transition phase from a native disorder conformation into a preaggregation state, which leads to fibrillization processes. Here we show the possibility to detect Tau in urine samples at sub-picogram level, through the concentration effect of the pyro-electrohydrodynamic (p-jet) technique. An immunofluorescence protocol is applied to concentrated p-jet spots able to reduce drastically the diffusion effects in the antibody-antigen reaction. A set of diluted samples were prepared, and the fluorescence signal was detected by a confocal scanner. We achieved an excellent linear response with a significant signal-to-noise ratio down to 0.25 pg/mL. In perspective, the technique could be integrated into a compact device to be used for monitoring the early stage associated to neurodegenerative syndromes in different scenarios such as for example in long-term human space exploration missions.

We describe a novel one-dimensional photonic crystal design allowing for the concurrent excitation of transverse-electric and transverse-magnetic Bloch surface waves, thus paving the way for polarization-resolved sensing experiments. We discuss its application for the surface-enhanced sensing of oriented DNA molecules through nanoscale birefringence measurements.

On December 5, 2022, Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) made history, demonstrating fusion ignition for the first time in a laboratory setting. NIF produced 3.15 megajoules (MJ) of fusion energy output using 2.05 MJ of laser energy delivered to the target, demonstrating the fundamental science basis for inertial fusion energy. In this presentation, the major large optic technology advancements that have enabled NIF today to routinely operate at now 2.2MJ, further aiding ignition experiments, are discussed. In addition, latest developments on fabrication processing science to aid in fabricating complex freeform optics with high precision for use in various laser systems are discussed.

U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-XXXXX

The laser-induced damage resistance of large optical components remains an important limitation for the maintenance costs, reliability, and further development of high energy/high-power (HE/HP) laser systems. With numerous manufacturers providing different laser-induced damage threshold (LIDT) values in the nanosecond regime, a simple ranking based on numbers alone may not provide a clear picture of the best choice. Variations in testing procedures, albeit following the ISO 21254 standard, further complicate the selection process. By employing a comprehensive 1-on-1 test procedure, it becomes possible to observe various parameters that influence LIDT values. An overview on how the laser beam size, the spectral characteristics of the tested optic and possible contamination of the surface are influencing the LIDT values will be presented.

The performance of an optical component or surface might quicky be limited by light scattering induced by the surface and coating roughness, as well as imperfections and contaminations. On the other hand, the scattered light contains valuable information about its source, which makes scattering based techniques powerful characterization tools for these important features. A major advantage is the fast, robust, and contact free measurement approach enabling even close-to process applications. Based on several examples we demonstrate the potential of light scattering characterization during the fabrication process up to even in-situ coating inspection.

NSOS-alpha is a 1.5-m aperture, F/1.55, wide field prime focus telescope for the Korea Astronomy & Space Science Institute (KASI) to discover and catalogue near-Earth asteroids, especially Potentially Hazardous Asteroids. Among the different optical designs, the current baseline is based onto a design with reduced sensitivities to both manufacturing and alignment tolerances, to optimize as-built performances instead of reducing nominal aberrations only. Different optimization techniques have been used and compared. As result, a fast and effective optimization procedure has been identified and implemented, and it will be used also during the manufacturing process to improve overall performance.

By using our Membrane-on-Fiber technology, we can design, fabricate and transfer complex semiconductor nanophotonic structures on the tip of optical fibers. We report fiber-tip sensors of refractive index, biomolecules, electric field and pressure, combining ease of fabrication and high precision. Using a strongly-localized and narrow-linewidth nanophotonic cavity, we also demonstrate the sensing of single ultrafine particles with diameters down to 50 nm.

Here we have developed an advanced surface-enhanced Raman scattering (SERS) platform that enables the ultrasensitive, rapid and highly specific identification of tumour biomarkers in liquid biopsies. Our focus is on the detection of Thyroglobulin (Tg), the most important tumour biomarker for the diagnosis and prognosis of thyroid cancer. Specifically, SERS-active substrates fabricated by nanosphere lithography on chip or on tips of optical fiber (OF) were functionalised with Tg Capture antibodies. Gold nanoparticles were functionalized with Detection antibodies and conjugated with a Raman reporter. The sandwich assay platform was validated in the planar configuration and a detection limit of only 7 pg/ml was successfully achieved. A careful morphological characterisation of the SERS substrates allowed us to strictly correlate the coverage area with the Tg concentration. The same approach was successfully demonstrated in the washout of fine needle aspiration biopsies from cancer patients. The strategy was transferred to the Lab On Fiber (LOF) SERS platform and successfully used to detect Tg concentration. The proposed SERS-enhanced immunoassay platform has proven to be highly versatile and can be used with both microfluidic chip POC devices and SERS-OF-based optrodes to perform sensitive, specific and rapid ex vivo assays for Tg detection in liquid intraoperative biopsies.

In this contribution, we propose the use of an advanced all-optical self-heated sensing platform for highly sensitive monitoring of the volumetric water content (VWC) in the soil. The sensor is realized by properly integrating, inside a standard metallic needle, a fiber optic heating device based on core offset light coupling method and a Fiber Bragg Grating (FBG) acting as thermal monitor. The performance of the proposed device was validated through a series of measurements in the range [9 - 36] %VWC in the soil temperature range between 5 and 40 °C. Collected results have demonstrated that the presented platform is able to perform highly stable, fast and robust measurements, with time response lower than 10 seconds. The possibility of tuning the value of the injected power according to the application makes the proposed sensing solution extremely flexible and versatile for its exploitation in large areas and/or long-distance.

We investigate the potential of forward-stimulated Brillouin scattering in optical fibers to detect changes of the fiber diameter with nanometer resolution

Strong coupling with light has emerged as a powerful tool for modifying the properties of optical materials. Typical systems are based on a fluorescent layer embedded in a single optical cavity, whereby the excitonic emission is converted into a polarized, energy-tunable and dispersive polariton emission. There, excitons and photons coexist in the same volume and therefore any change in the emission properties of the excitonic material comes at the expense of simultaneously modifying the photonic environment where excitons reside, i.e., layer thickness and refractive index. Here, we demonstrate remote control over the intensity and total decay rate of the fluorescent layer by adding an extra purely photonic cavity strongly coupled to the first one. By modifying the resonant condition of the extra cavity, we reduce the total decay rate and suppress the fluorescence intensity of the fluorescent layer without explicitly affecting the first cavity. Such modification of the optical properties of the layer is the consequence of a resonant configuration that spatially segregates photons and excitons into different cavities.

Thanks to their excellent photoluminescence quantum yields, their facile and low-cost production, and their processing versatility, CsPbBr3 perovskite nanocrystals (NCs) stand out as excellent candidates to implement light-emitting devices. Elucidating their stimulated emission mechanisms is fundamental to achieve much more efficient and versatile perovskite lasers. In particular, two questions remain open: why the Amplified Spontaneous Emission (ASE) band is significantly shifted from the fluorescence one, and why the former seems to suddenly emerge from, and coexist with, the latter. These characteristic features have led to a debate, which is not settled yet, on which is the mechanism behind the ASE band shift. In this communication, we try to settle this debate and address these questions through experimental ASE measurements combined with numerical simulations. We show that the ASE behaviour in CsPbBr3 NCs thin films stems from a combination of reabsorption, excited state absorption, excitation of differently polarized waveguide modes, and the coexistence of short- and long-lived localized single excitons. The results in this work help understanding the stimulated emission mechanisms in perovskites and provide insightful information on research avenues to increase the efficiency of the light-emitting devices based on these materials.

Year by year, the importance of plastic nanostructures in photonics is increasing. Indeed, polymers represent an interesting alternative to more traditional metal oxides, being easily processable and allowing for light, free-standing and flexible structures. In the field of energy efficiency and sustainability, we bring in two positive examples of the use of plastic photonic crystals: sensing and thermal shielding. In sensing they allow for easy detection of analytes, such as the byproducts of food degradation; a colour change identifies the spoilage, with possible application of these plastic sensors in smart packaging applications. On the other hand, they can be of interest for thermal shielding applications. Indeed, they can be engineered as thin, transparent films able to reduce indoor heating by sunlight and in turn the energy consumption related to the use of air conditioning.

A Tm:LiYF4 laser operating on the 3H4 → 3H5 transition is integrated into a high-power diode-pumped Nd:ASL laser for intracavity upconversion pumping at 1.05 µm. This architecture leads to a record-high output power at 2.3 µm ever extracted from any upconversion pumped Thulium laser. The continuous-wave Tm-laser yields 1.81 W at 2.3 μm at 32 W of laser-diode pump power at 0.8 µm, rivalling direct diode pumping. The intracavity pumping mitigates weak absorption inherent to the upconversion pumping scheme and disperses the deposited heat over two laser crystals. This laser design minimizes heating of the Tm-crystal and enhances the tolerance to Tm3+ excited-state absorption, being promising for high-power 2.3-µm solid-state lasers based on thulium ions.

We report on an original chaotic dynamic behaviour of a passively Q-switched 2.3-µm Thulium laser operating on the 3H4 → 3H5 transition. The experiment employs a Tm:LiYF4 laser crystal within various laser cavity configurations, involving optional additional cascade laser operation on the 3F4 → 3H6 transition at 1.9 µm. The saturable absorber employed is Cr2+:ZnSe, which is exclusively saturated by the 2.3 µm laser emission. A precise analysis of the Q-switching dynamics shows a pronounced inclination of the cascade laser scheme towards chaotic operation. To investigate the origins of chaos, we originally monitor the metastable 3F4 level population using cascade laser operation at 1.9 µm, which proves to be a crucial underlying parameter for explaining the observed instabilities. This analysis allows for explaining the specific dynamics of the Q-switched 2.3 µm Tm-laser intrinsically linked to Tm3+-doped materials. A very atypical route to chaos for a Q-switched laser is demonstrated involving type I intermittencies. The obtained results are of great interest for studying the premises of chaos in pulsed solid-state lasers.

We study the spatiotemporal dynamics of asymmetric microcavity semiconductor lasers as function of the resonator geometry. Our experimental and numerical studies elucidate how the classical ray dynamics, dictated by the cavity geometry, affects nonlinear light-matter interaction, which in turn determines lasing dynamics. Our approach to engineering laser dynamics is robust, compact, and has the potential to be applied to controlling other nonlinear complex systems.

We demonstrate a novel and straightforward approach to enhance the nonlinear responses of metamaterials by incorporating them into multipass cells, allowing the pump beam to interact with the metasurface multiple times. As a proof of principle, we achieved phase matching of the second-harmonic generation (SHG) signal with a superlinear dependence on the number of passes. Experimentally, we observed a remarkable tenfold enhancement in the SHG signal from a plasmonic metasurface after nine passes.This approach is generic and compatible with various existing enhancement techniques and metamaterials, offering a versatile method to improve the performance of nonlinear devices.

Recently, superradiant bursts of light have been experimentally observed for a cascaded quantum system. This was realized using an ensemble of waveguide-coupled two-level atoms that exhibit propagation direction-dependent coupling to the waveguide mode. Here, we experimentally study the collective radiative decay of a fully inverted atomic ensemble and measure the second-order correlation function, g^(2)(t1,t2), of the light emitted by the atoms into the waveguide. We observe a g^(2)(0,0) of about 2 at the beginning of the decay, followed by a decrease to g^(2)(t,t) to 1 (where t>0) within the characteristic time scale of the burst dynamics. This built-up of second-order coherence can be interpreted by assuming that, following an initially independent emission, the atoms synchronize during their decay. Interestingly, for ensembles below and above full inversion, g^(2)(t,t)=1 for all times. In addition to these observations, we find an anti-correlation of photon detection events, i.e., g^(2)(t1,t2)<1, in certain parameter regions in which t1 unequal to t2, indicating a temporal sub-structure of the light emerging the ensemble. Our findings can be well described with a model based on the truncated Wigner approximation. Our results contribute to understanding the fundamentals of light-matter interaction and help engineering protocols for the generation of non-classical light.

The Advanced Laser Light Source (ALLS) laboratory provides high-repetition-rate ultrashort light pulses using ytterbium laser technology. Recently, we have developed a novel end-station called time- and angle-resolved photoemission (TR-ARPES) to explore the rapid electron dynamics in quantum materials when subjected to intense optical excitation in the near- and mid-infrared range. These intense pulses are generated using our in-house-built optical parametric amplifier (OPA) ranging from 1.6 to 8 μm with a duration of around 100 fs

Recent years have witnessed remarkable progress in enhancing the supercontinuum (SC) generation in highly nonlinear photonic integrated waveguides. In this study, we conduct a comprehensive investigation into supercontinuum (SC) generation in high-index doped silica glass integrated waveguides. We explore a variety of femtosecond pumping wavelengths and input polarization states, demonstrating coherent octave-spanning SC bandwidth from visible to mid-infrared wavelengths.

The conventional detection of Forward Brillouin Scattering (FBS) in optical fibers requires of interferometric techniques using lengths of tens of meters. In this paper, we demonstrate an alternative approach that provides efficient and high-resolution detection of FBS signals, while using just a 20 cm length section of bare fiber. It consists of a pump and probe scheme using a fiber ring resonator as the interrogation system of the mechanical vibration, which modulates the resonances. The result is an amplitude modulated optical trace which allows the detection of resonances R_(0,m) and TR_(2,m).

This work proposes a signal processing algorithm to analyse the optical signal from a Low

Coherence Interferometric (LCI) system. The system uses a Mach-Zehnder (MZ) interferometer to interrogate

a Fabry-Perot cavity, working as an optical sensor. This algorithm is based on the correlation and convolution

operations, which allows the signal to be reconstructed based on itself, as well as, on the linearization of the

signal phase, allowing the non-linearities of the actuator incorporated on the MZ interferometer to be

compensated. The results show a noise reduction of 30 dB in the signal acquired. As a result, a reduction of

8.2 dB in the uncertainty of the measurement of the physical measurand is achieved. It is also demonstrated

that the phase linearization made it possible to obtain a coefficient of determination (namely, R-squared)

higher than 0.999.

We have developed a fast, high-resolution, and single-shot lensless imaging technique based on the wavefront folding interferometer (WFI). Considering a stationary, quasimonochromatic, and quasihomogeneous source of light we studied the effect of spatial coherence on the retrieved image quality. Moreover, a thorough investigation of the resolution and the semi-infinity depth of focus of the imaging system was performed and demonstrated experimentally.

Terahertz Nonlinear Ghost Imaging introduces a groundbreaking method for object sampling at spatial-temporal levels, achieving super-resolution (i.e., beyond the diffraction limit). Our theoretical and experimental endeavour seeks to leverage this technique, enabling arbitrary field-level waveform manipulation through intricate propagation in scattering environments. This approach facilitates essential agile waveform adjustment, made possible through near-field interactions between terahertz sources and scattering media.

Road markings (RM) consist of two distinct layers: the paint layer and the retroreflective layer. Together, they function as system and are essential features for road safety. Recent studies have been centred on elevating these systems to a smarter level, imbuing them with novel functionalities, increasing their visibility, service life and road safety. These new capabilities encompass photoluminescence, anti-aging, self-cleaning, and thermochromism. The aim of this study is to review the advancements and highlight potential opportunities for RM, the materials employed, functionalization techniques, and the key outcomes achieved.

Optical affinity biosensors with single molecule sensitivity are reported based on a combination of optical and molecular interaction - based amplification. Plasmonically-enhanced fluorescence detection that is suitable for readout of sufficiently large sensor surface areas is implemented by the use of tailored metallic nanostructures. These metallic nanostructures are chemically modified with antifouling polymer-based biointerfaces for specific capture of target molecular species. The response to specific affinity binding events is further enhanced by rolling circle amplification, through enzyme-free catalytic hairpin assembly method, and affinity mediated transfer, in order to associate the individual affinity capture target molecules with bright fluorescence spots enabling counting of affinity captured target molecules (‘digital assay format’). The presented methods will be put to context with liquid biopsy – based lung and melanoma cancer diagnostics through ultrasensitive detection of trace amounts of specific biomarkers circulating in blood.

Support from Gesellschaft für Forschungsförderung Niederösterreich m.b.H. project LS20-014 ASPIS, Austrian Science Fund via the project DIPLAB (I 5119-B and 21-16729K), Czech Science Fund through the project APLOMA (22- 30456J), European Union’s Horizon Europe program project VerSiLiB (No 101046217) and Operational Programme Johannes Amos Comenius financed by European Structural and Investment Funds and the MEYS (Project No. SENDISO -CZ.02.01.01/00/22_008/0004596) is acknowledged.

Over recent decades, metallic nanostructures have emerged as pivotal components in biosensing applications due to their exceptional optical transduction properties. In this study, we present a novel approach by integrating hybrid plasmonic/dielectric materials to enhance the sensitivity of large-scale plasmonic arrays. Specifically, we propose refining the fabrication process for Gold Nanomushrooms by incorporating dielectric Silicon Nitride instead of traditional pillars. This strategic modification aims to yield sensors with a heightened responsiveness to refractive index variation, tailored to address the needs of biomedical applications.

A Metal-Enhanced Fluorescence (MEF) based immunosensor has been developed for the detection of prostate-specific antigen (PSA), a crucial biomarker for prostate cancer. The biosensor consists of gold nanoparticles (AuNPs) randomly immobilized onto a glass substrate via an electrostatic self-assembly technique. A sandwich scheme has been employed for PSA recognition, with antibodies as capture bioreceptors covalently immobilized onto the AuNPs surface and a top fluorescently labeled bioreceptors layer. The biosensor has been tested on real samples, successfully detecting PSA in human serum within a rapid 40-minute assay time, achieving a limit of detection (LOD) of 150 pg·mL-1.

We recently developed a peculiar disaggregation‒based colorimetric sensing scheme where stable and reversible clusters of functionalized Core@satellite magnetic nanoparticles (CSMPs) are first created by surfactant‒induced depletion‒related forces and then fragmented in response to the detection events. The fragmentation of CSMPs clusters entails an unexpected increase of the extinction intensity of the colloids. Here, we provide a theoretical foundation for such optical behaviour by first modelling both the CSMPs and CSMPs clusters, and then investigating their optical response by finite-difference time-domain simulations.

This paper presents the design and implementation of a tailored optical system for rapid characterization of transmission-based localized surface plasmon resonance (LSPR) biosensors. The system incorporates a motorized monochromator, offering extreme versatility in experimenting with wavelength resolution and bandwidth of the illumination. This setup streamlines the process of determining optimal chip design parameters such as the density of nanoparticles and the number of detection wavelengths required, as measurements are fully automated and software-driven. Furthermore, the system facilitates straightforward detection of manufacturing errors, including misaligned spots or inhomogeneous particle distribution, enhancing overall efficiency and reliability in biosensor evaluation.

The flexible and efficient production of precise optical free-form surfaces requires advanced kinematic operating principles. Due to the complex surface geometries, polishing processes with point or linear contact are used. These generally result in longer polishing times due to the smaller footprint compared to large-area polishing tools. The creation of a high precision, polishable surface in the shaping steps of the process chain is therefore of great importance. This applies in particular to minimising the roughness, but also the depth of SSD (sub-surface damage) and the mid-spatial frequency errors before the polishing process. The article describes selected process chains for the production of free-form optics and presents options for optimising the required polishing steps.

A new concept for polishing pads for flat and spherical surfaces is introduced which comprises additive manufactured polishing pads made of cerium oxide. By using additive manufacturing technologies in polishing processes with polishing slurry, those processes can be substituted with tools containing bonded grain. The bonded polishing pads can be fabricated using rolling processes. The pad geometries can be adjusted by using laser cutting. Furthermore, surface modifications of the pad can be applied with laser processes as well to favour quality and economic factors of polishing processes. First results from the experimental setup are showing, that lapped surface with a roughness Rq of ~500 nm can be polished to approx. 30 nm roughness Rq by polishing with pads using bonded grain cerium oxide foils.

Different Light-based techniques for 3D printing have been developed such as SLA and DLP that use single photon absorption and direct writing by scanning a focused spot using two photon absorption. These techniques employ a layered approach using incoherent imaging. Herein, we propose a layerless approach using coherent holographic projection which is based on Tomographic Volumetric Additive Manufacturing (TVAM). We demonstrated this concept by implementing a volumetric printer using a Digital Micromirror Device (DMD) in a Fourier configuration and showing its capabilities by printing a micrometric scale object. The use of the Lee holograms method allows us to use the DMD as a fast phase modulator, and the combination of tiling holograms with Point Spread Function (PSF) modifications allows us to reduce speckle noise and provide three-dimensional control of the projections. We use these holographic projections to fabricate millimetric 3D objects in less than a minute.

We here present our research into application-adapted laser beam shaping which enables the generation of tailored light volumes, explicit optimization of the temperature distribution within a work piece and high-fidelity beam shaping in combination with optical amplifiers.

Brillouin scattering has found extensive applications in advanced photonics functions, including microwave photonics, signal processing, sensing, and lasing. More recently, it has been employed in micro- and nano-photonic waveguides. Tapered optical fibers, due to their small transverse dimensions, exhibit a range of optical and mechanical properties that render them highly attractive for both fundamental physics research and technological applications. By employing a heat brushing technique, we can create suspended subwavelength silica rods over several centimeters with minimal loss. In contrast to standard telecom fibers, where Brillouin scattering is characterized by a single Lorentzian resonance centered at 10.86 GHz (@ 1550 nm), tapered silica fibers exhibit multiple Brillouin resonances at various frequencies ranging from 5 GHz to 10 GHz, originating from surface, shear, and compression elastic waves. Surface acoustic waves are sensitive to their environment, while compression waves efficiently convert light. Recently, we demonstrate that a large evanescent optical field surrounding the nanofiber, exibit an efficient Brillouin scattering in gas. We show drastic Brillouin scattering enhancement by increasing the gas pressure (CO2, 47 Bar) with a maximum Brillouin gain which is 79 times larger than in a SMF.

In this paper, we have presented a novel and compact bicolor Bessel beams (bi-BBs) generator based on a single-mode fiber integrated with an axicon-like microstructure (AM). The proposed design utilized two Bessel beams manifested as pump beam of circular distribution at λ=405 nm and STED beam of donut distribution at λ=532 nm. Through numerical simulations, a type of AMs has been found to support STED system light source. The influence of the AM size variance on the characteristics of bi-BBs was also investigated. With optimized AM, the bi-BBs emitted from a single-mode fiber greatly reduces the coaxial alignment difficulty of the free space STED systems and may also provide a new way to achieve mirrorless STED super-resolution systems.

We present the design of composite optical nanofibers coated with different nonlinear materials (PMMA and TiO2) for the realization of new all-solid Raman wavelength converters. Two coating processes, multilayer dip-coating and atomic layer deposition, have been successfully developed and optimized for the functionalization, inducing only relatively low losses comprised between 0.5 dB and 1.76 dB on 2 cm. Encapsulation has also been demonstrated. The Raman modal gain coefficients have been calculated to lie between 0.3 and 0.4 m-1W-1. Based on our previous results obtained with nanofibers immersed in different liquids, Raman threshold in the ns second regime should be obtained with few cm long nanofibers. This work opens the way to a new family of composite nanofibers for different applications in nonlinear optics.

We explore fiber Fabry-Pérot (FFP) resonators, a new platform for frequency comb generation We experimentally identified mirror diffraction losses dependent on the effective area of the fiber and simulated them via Fourier optics. In the nonlinear regime, a linear stability analysis of a generalized Lugiato-Lefever equation revealed optimization of reflectivity and detuning, leading to a significant reduction in the required power threshold for comb generation compared to linear regime, and to improved energy frugality. Furthermore, controlled or exploited birefringence in various experimental settings enabled the generation of Kerr frequency combs and stimulated Brillouin lasers. In this communication we propose an overview of the practical characteristics related to the fabrication and use of these resonators.

An innovative integration method was recently proposed to integrate miniaturized optical sources on the facet of an optical fiber in a monolithic fashion. Recent advancements concerning the coupling efficiency improvement will be presented.

We present a functional glass coating that embed several functionalities suitable for cover glass

applications in solar energy harvesting applications, including omnidirectional anti-reflection, dynamic solar

control, and self-cleaning. Yttrium hydride oxide (YHO) and sulphated titania (SO4-TiO2) thin films were

deposited on the nanopillar structures using magnetron sputtering methods. Nanopillar terminated glass were

achieved by colloidal lithography templating methods on iron free glass, realizing nanopillar structures with

dimensions /2. The resulting nanopillar structures exploit Mie scattering for wide angle light collection.

The YHO and SO4-TiO2 films block UV light and YHO photo-darkens upon solar light absorption with and

reverts to its transparent state in darkness in reproducible manner with colour neutral spectral characters. The

results demonstrate possibilities to increase e.g. solar cell device efficiency by smart cover glass materials

without adding further control and maintenance solutions.

The controlled manipulation of optical responses from quantum emitters on the nanoscale is crucial for creating tunable light sources in nanophotonic devices. In this work, we study the coupling of a thin film made of phase-change material (VO2) with a 20 nm-thick silica layer containing Er3+ ions. We demonstrate that the thermally induced semiconductor-to-metal transition of VO2 enables the dynamic tuning of the local density of optical states near erbium emitters. This modulation enables the real-time control of Er3+ emission lifetime at the telecom wavelength (1.54 μm). We achieve a decay rate contrast of factor 2 between high temperature, when VO2 is metallic and room temperature, when VO2 is semiconductor. The experimental findings are in excellent agreement with predictions obtained using the classical dipole oscillator analytical model. A complete hysteresis cycle is measured by varying the sample temperature in the range between room temperature and 100 °C. The hysteresis parameters are consistent with those obtained by GIXRD and transmittance measurements of the VO2 layer as a function of the temperature, confirming the active role provided by the phase-change material. The results make the investigated system an optimal candidate for the development of tunable photon sources at telecom wavelength.

Erbium-doped “mixed” yttria-scandia (ScxY1-x)2O3 transparent laser ceramics were fabricated by vacuum sintering at 1750 °C from laser-ablated nanoparticles. Their absorption and mid-infrared emission properties were studied. The addition of Sc3+ induces a strong inhomogeneous spectral line broadening, modifies the crystal field and affects the distribution of Er3+ ions over C2 and C3i symmetry sites. Due to their broadband emission properties, Er:(ScxY1-x)2O3 ceramics are appealing for 2.8-µm lasers.

Depressed cladding waveguides in a Dy:YAG crystal were fabricated by femtosecond direct laser writing. Their μ-luminescence characterization in the visible revealed well-preserved emission properties in the core region, a strong material modification within the damage tracks, and an anisotropic stress field associated with ear-like side structures. The developed waveguides are promising for yellow lasers.

We use spatial light modulation to investigate the diffractive effects of gravitational lensing in the laboratory. Using this new platform for laboratory astrophysics, we can overcome the coherence challenges that prevent the observation of diffraction in astronomical imaging. These studies will inform gravitational lensing of gravitational waves when imaging of gravitational waves becomes available. Our previous work involved studying lensing by a single mass, symmetric and elliptical. This work focuses on the patterns produced by a binary-mass system. We observed rich 2-dimensional interference patterns bounded by caustics. Comparison of experimental results with preliminary theoretical calculations is excellent.

The dichroic macular pigment in the Henle fiber layer in the fovea enables humans to perceive entoptic phenomena when viewing polarized blue light. In the standard case of linearly polarized stimuli, a faint bowtie-like pattern known as the Haidinger's brush appears in the central point of fixation. As the shape and clarity of the perceived signal is directly related to the health of the macula, Haidinger's brush has been used as a diagnostic marker in studies of early stage age-related macular degeneration (AMD) and central field visual dysfunction. However, due to the weak nature of the perceived signal the perception of the Haidinger's brush has not been integrated with modern clinical methods. Our group has developed techniques to increase the strength of the perceived signal by employing polarization coupled orbital angular momentum states. We successfully achieved the creation of stimuli with higher numbers of azimuthal fringes, enabling the perception and discrimination of Pancharatnam-Berry phases, measuring the visual angle of entoptic phenomena, retinal imaging using structured light, and the creation of radially varying entoptic stimuli. Our current studies are focusing on applying the structured light toolbox that we developed to subjects that suffer from ocular diseases such as AMD.

Photonic Orbital Angular Momentum (OAM) is becoming a pertinent quantum variable for atom-light interaction, in particular for non-linear interaction which leads to photon entanglement and OAM-entanglement. With two 4-levels atomic schemes, we show that Four Wave Mixing addressed by vortex beams leads to very different OAM-entanglement especially for large OAM values.

We introduce a cutting-edge technique utilizing structured light, specifically linear photonic gears, for ultra-sensitive transverse displacement measurements. Light propagation through periodic liquid-crystal metasurfaces translates displacements into polarization rotations of a laser beam. The system's sensitivity can be enhanced by decreasing the spatial period of these components, achieving resolutions of 400 pm under standard conditions and potentially 50 pm with optimized setups. This compact, cost-effective approach offers high stability and precision, demonstrating significant advancements in applications such as precision component monitoring, material property assessments, and nanofabrication, showcasing the transformative potential of structured light in precision measurement technologies.

We consider a far-red-detuned optical cavity, driven by a pump, which contains an ultracold atomic medium. Using coupled partial differential equations which describe the evolution of the atomic and optical fields, we demonstrate that our model leads to novel self-structuring, led by the optical field through the dipole force, within the ultracold atomic medium. Introducing OAM to the optical pump, we demonstrate that these structures may be made to rotate, forming atomic fields analogous to persistent phase currents.