Holographic multimode fibre endoscopes have established themselves as a tool for minimally invasive imaging, with particularly promising applications in the domains of neurobiology. These instruments allow imaging of previously inaccessible deep brain regions of living animals models. In all these applications, wavefront shaping is used to holographically control the input light fields entering the multimode fibre, with it being treated purely as a complex medium. Yet, multimode fibres exhibit symmetries and strong input-output field correlations, which are distinct for step-index and graded-index multimode fibres. In this work, we appropriately leverage these correlations to enable high-quality focussing of pulsed lasers with minimal intermodal dispersion. Such effect is then used as the underlaying basis for delivering pulsed super-resolution STED microscopy through a custom multimode fibre endoscope comprising input-output correlations of both step-index and graded-index fibre types. We show resolution improvements over 3-fold beyond the diffraction limit and showcase its applicability to bio-imaging. This work offers a solution for delivering short pulses through step-index segments and represents a step towards enabling advanced imaging techniques with virtually no depth limitation.

Lensless endoscopy enables minimally invasive imaging of biological tissues, particularly in the brain. However, miniaturization and optical performance remain key challenges. Multicore fibers (MCFs) are promising probes, where beam shaping at the output is typically achieved using Spatial Light Modulators (SLMs) at the input. Even though SLMs are active components, they require bulky optical elements and have efficiency and speed limitations.

Metasurfaces offer a compact alternative for wavefront shaping. By integrating them with MCFs, we aim to create a highly flexible two-photon endoscope. Metasurfaces can perform phase and group delay compensation with improved resolution while significantly reducing system footprint, as they match the fiber’s dimensions.

We characterize fiber transmission and metasurface performance. First, we measure the fiber’s transmission matrix, determine the required curvature for focusing, and fabricate the metasurface via lithography and etching. After fabrication, phase and transmission measurements validate its optical response. The metasurface is then imaged at the fiber input to realise the focusing at the output.

Our demonstration features a scanning endoscope using a passive metasurface for phase compensa-tion and focal spot generation, with beam scanning controlled by galvo mirrors. Finally, we discuss future prospects, including group delay compensation and active metasurfaces for dynamic wave-front control.

We propose a new spectroscopy technique in the mid-infrared (MIR) domain without any cryogenic system. The MIR field emitted by the source is shifted to the near-infrared using sum-frequency generation in a Periodically Poled Lithium Niobate ridge waveguide, and is then detected in the photon-counting regime using a low-noise SiAPD detector. The non-linear process is powered by a continuously tunable pump laser. We present here an experimental proof-of-concept, where the light emitted by a thermal source in the 3-4μm band is spectrally modulated using a Michelson interferometer. By continuously tuning the pump laser wavelength between 1058nm and 1078nm, the MIR spectrum is reconstructed, and the imposed spectral modulation period is retrieved successfully with a relative error of less than 5%

In this work, we present a novel approach to determine the refractive index n and the extinction coefficient κ from terahertz time-domain spectroscopy (THz-TDS) measurements using artificial neural networks (ANNs). We train the network in our experimental datasets to create a model that can accurately and efficiently calculate these material properties, the proposed neural network is superior to traditional analytical methods, which rely on approximations, and a faster and easier alternative to iterative root-finding algorithms. Our results demonstrate that this machine learning methodology solves common issues in THz-TDS data analysis, such as phase unwrapping, time-domain windowing, low computation rates, and high accuracy at low-frequency regions, effectively and achieve results with high accuracy.

Crude oils extracted from Kuwait oil wells were investigated using Far-infrared Transform Spectroscopy technique and compared to quantum chemistry calculation. Experimental data showed absorption peaks at 198 cm-1, 254 cm-1, 429 cm-1, and 528 cm-1. On the other hand, the calculated spectral bands of several alkane molecules were found near the experimental absorption bands that different level of calculation revealed more accurate assignment. Although only two bands were predicted by the calculation, adding alkane molecules of different lengths (pentane to decane) resulted in the formation of new bands. These preliminary results suggest that there is a mixture of different alkanes present in the investigated samples, a typical characteristic of unprocessed crude oil.

Transparent ceramics of Holmium-doped yttria (Ho:Y2O3) were fabricated by Hot Isostatic Pressing at 1720 °C / 190 MPa in argon, and the effect of YF3 addition on their microstructure, optical, vibronic and infrared emission properties was studied. The fluorine addition improves the ceramic transparency, accelerates the grain growth and enhances the luminescence lifetimes of Ho3+ states responsible for emissions at 2 µm and 3 µm.

In the context of the quest of organic laser diode, we propose a method to compare organic gain semiconductors in terms of laser threshold before integrating them into laser cavity. This method is based on three types of measurements for each material: 1-measurements of absorption and photoluminescence spectra to evaluate the re-absorption, 2-measurement of fluorescence lifetimes linking the potential laser gain to the current in the diode and 3-measurement of the gain of the amplified spontaneous emission. This approach is validated by laser threshold measurements carried out under optical pumping for two organic compounds DCM and DCJTB deposited on laser cavities

We report on a comprehensive spectroscopic study of singly Dy3+ doped and Er3+,Dy3+ codoped calcium fluoride (CaF2) crystals for midinfrared laser applications. The f-f transition probabilities of Dy3+ were determined by the Judd-Ofelt theory. The stimulated-emission cross-section reaches 0.25×10-20 cm2 at 2.93 µm corresponding to an emission bandwidth of 350 nm. The Er3+ → Dy3+ energy transfer efficiency in codoped crystals is quantified. The 4.4-µm Dy3+ emission is observed for the first time from fluorite crystals.

Surface-doping of lithium niobate wafers with rare earth or optically damage-resistant ions by physical vapour deposition and high-temperature in-diffusion is a cost-efficient and flexible method for the fabrication of thin-film LN or LNOI with dopants which are not common in crystal growth. LNOI doped with different concentrations of Er, Yb, Tm, Pr, Zn and Zr has been fabricated. As an example, the fluorescence spectra of Er:Yb:LNOI samples were recorded, and a high small-signal gain of 35 dB/cm was measured in ridge waveguides.

The objective of this work is to design a secondary luminescent concentrator (LC) -optically pumped by a YAG:Ce primary luminescent concentrator- then emitting photons between 1.0 and 1.5 µm in the SWIR. The main properties should be a good overlap of the absorption spectrum with the YAG:Ce emission, a high quantum efficiency value for the Ni2+ emission, and a good optical quality of the crystal to limit losses. Ni2+ doped lasers crystal such as LaMgAl11O19:Ni and YAlO3:Ni or LiGa5O8:Ni glass-ceramics can be proposed and are investigated within this work.

Lanthanum oxysulfide powders doped with Erbium ions were fabricated by the combustion method followed by sulfurization at 1000 °C under H2S + N2 atmosphere. X-ray diffraction confirms their single-phase nature (sp. gr. P-3m1). Raman spectroscopy reveals a maximum phonon energy of 389 cm-1. The effect of Er3+ doping level (0.5 – 7 mol%) on the visible and mid-infrared emission properties of Er:La2O2S was studied.

Multi-band systems have demonstrated to be a viable solution to sustain capacity growth required by optical communication systems, thanks to the availability of wide bandwidth amplification technologies, like the Raman amplifier (RA). However, extreme levels of optimization are needed to extract all the potential, requiring super-fast and accurate evaluation of the impact of nonlinear effects. This is a tricky task when the transmission bandwidth is very large, as all fiber parameters becomes frequency dependent and the number of data channels and RA pumps is large. Also, the inter-channel stimulated Raman scattering (ISRS) become impactful.

Optimization approaches based on Gaussian Noise (GN) models turn to be very complex, with a consequent slow down of the whole design process. Even using the fast GN-based closed-form-models (CFMs), it requires a full spectral and spatial knowledge of the signal power profile along the fiber span. This is particularly computational heavy when backward RA is considered. We propose an approach based on machine learning (ML) and neural networks (NN) to accelerate the process. The method, tested for a super-(C+L) system (12 THz bandwidth) and backward Raman amplification, guarantees a high level of accuracy and a significant speed increase.

Advances in fibre design, particularly through spatial multiplexing strategies such as multi-core and multi-mode fibres, have shown significant promise. This talk reviews key fibre design innovations aimed at capacity maximisation, exploring core design optimisation, modal dispersion management, and reduction of inter-channel interference. Practical challenges, recent breakthroughs, and future directions in designing optical fibres for maximised capacity and improved performance in next-generation high-capacity systems will be discussed.

We use X-ray computed nanotomography to characterize an optical fiber taper used for nanofiber-based sensors. The resolution achieved goes far beyond the capability of standard optical computed tomography devices.

In this work, we numerically investigate the gain properties of an Yb3+:Er3+:Tm3+:Ho3+ co-doped optical fiber amplifier. The numerical simulations show that a gain higher than 15 dB in a wavelength range of 300 nm can be achieved. The erbium amplifies in the well-known C-band, while thulium and holmium amplify from 1760 nm to 2030 nm.

We demonstrate centimeter-scale dual-wavelength digital holography with expanding wavefront illumination that overcomes pixel-size resolution limitations thereby achieving a diffraction-limited spatial resolution of 3.91 micrometer compared to pixel-size limited resolution of 6.9 micrometer. The proposed holographic scheme provides an efficient, high-speed, high-resolution 3D optical inspection tool for industrial metrology.

This work presents a data-driven approach for reconstructing the longitudinal

component of tightly focused optical fields using only experimentally

accessible polarimetric intensity images. A custom-designed deep neural network

is trained on simulated polarimetric mappings generated from aberrated

wavefronts through a high-NA objective. The model successfully reconstructs

the complex amplitude of the longitudinal field with high fidelity, offering a

practical and instant method for indirect measurement of longitudinal components

in tightly focused beams.

A valuable method in biological imaging is Oblique Plane Microscopy (OPM), in which a single objective lens is used to launch a tilted (oblique) light sheet into the sample and to capture the fluorescence emission light. The captured light can be focused remotely onto a glass-immersion objective, tilted to match the oblique light sheet. Combined with this bespoke objective, OPM enables the use of a high-NA, short working distance objective with high magnification, maximising resolution and fluorescence capture efficiency.

Accurate modelling of the OPM’s 3D Point Spread Function (PSF) is needed for performance and resolution analysis, image deconvolution, and combinations of OPM with Structured Illumination Microscopy (SIM). The high NA necessitates taking into account all effects of polarisation and all directions of propagation, the remote focusing construction, and the non-orthogonal optical axes of the different lenses. We have developed a fully exact vectorial model of the 3D PSF for OPM. Key elements are the vignetting and deformation of the different non-overlapping pupil planes in the optical train, and correct handling of the remote focusing. It appears that a modification of standard Fourier optics methods using non-Cartesian coordinate frames provides an efficient route to compute the 3D PSF.

Icosahedral colloidal supraparticles are of interest because of their strong spherical symmetry. A polarization-complete tomographic imaging technique is developed to study the scattering properties of icosahedral supraparticles. The results reveal that our particles exhibit angle-dependent scattering behavior and inner structures.

In this talk, we discuss the effect of plasmonic resonances on the Fisher information in the far field. We consider a metallic nanowire embedded in a silicon substrate, illuminated by a dark-field focused spot, and we investigate how its position can be estimated from the scattered far-field intensities. The Fisher information is computed for both lateral and longitudinal displacements of the nanowire, and the dependence on the illumination frequency is analyzed. We compute the complex resonance frequencies of the nanowires and show that frequencies near the real part of the plasmonic resonance frequency enhance the Fisher information. However, at the resonance frequency itself, the Fisher information drops sharply, leading to an Information Dark State in which the position of the nanowire becomes nearly undetectable. This effect is analyzed and illustrated for both gold and silver nanowires.

Optical metasurfaces have emerged as powerful, flat photonic elements capable of tailoring light at the sub-wavelength scale. In particular, quasi-bound states in the continuum (qBIC) metasurfaces enable the creation of high quality (Q) factor resonances in ultrathin nanophotonic structures, offering a promising route to enhanced light–matter interactions. In this talk, I will present our recent advances in integrating van der Waals (vdW) materials with qBIC metasurfaces to realize robust exciton–polaritons. We first demonstrate self-hybridized polaritons in patterned WS2 metasurfaces, where the interplay between excitons and engineered photonic modes leads to Rabi splitting above 100 meV, in ambient conditions. Furthermore, we explore hBN-based dielectric metasurfaces supporting ultra-high Q resonances, with values exceeding 2000 across the visible range. Finally, by vertically stacking hBN with WS2 monolayer semiconductors, we realize room-temperature exciton-polaritons in vdW heterostructures, with nonlinearities three orders of magnitude larger than previous approaches. Our results pave the way for compact polaritonic devices with enhanced nonlinear responses, offering new avenues for low-threshold condensation and coherent photonic circuits operating at room temperature.

We present a hydrodynamic model based on Madelung's approach to describe the plasmonic properties of anisotropic materials. In this modelling, nonlocal effects arise from the Bohm potential and Thomas-Fermi quantum pressure.

We find exact formulas for the dispersion relation of magnetoplasmons and the optical conductivity, considering nonlocal effects. We apply them to monolayer phosphorene, a two-dimensional material known for its anisotropic properties. The plasmon dispersion of our model matches well with results from first-principles calculations.

Our findings show that including nonlocal and quantum effects explains why phosphorene does not support hyperbolic surface plasmon polaritons. This highlights the importance of going beyond simple models when studying materials that can support tightly confined plasmon-polaritons.

We explore the nonlinear optical properties of graphene and phosphorene nanoribbons using ab initio modeling and self-consistent perturbation theory. These two-dimensional materials exhibit significant potential for frequency conversion, optical modulation, and ultrafast signal processing due to their inherent nonlinear responses and tunable plasmonic characteristics. Our investigations reveal that graphene nanoribbons (GNRs) photoexcited by intense ultrashort optical pulses exhibit strong transient nonlinear optical responses driven by thermally activated plasmons, demonstrating a robust, non-invasive method for achieving tunable nonlinear effects without the need for excessive charge carrier doping. In a parallel study, we investigate enhanced nonlinear interactions in nanoribbon heterostructures, where the synergetic combination of tunable plasmons and anharmonic electron dispersion in graphene and phosphorene offers unique opportunities for device engineering.

Heavily doped semiconductors have emerged as an enabling platform for mid-infrared photonics, leveraging free electrons to achieve strong and tunable nonlocal-nonlinear light-matter interactions. In this talk, we will discuss recent theoretical and experimental studies on third harmonic generation and Kerr nonlinearity in heavily doped semiconductors, in which hydrodynamic contributions dominate.

The introduction of genetically expressed photosensitive proteins to optically control and monitor neuronal activity has opened new avenues for minimally invasive investigation of the brain, giving rise to the field of optogenetics.

Fully harnessing the potential of these tools has required the development of dedicated optical strategies. In particular, the use of two-photon infrared excitation combined with light-shaping techniques has enabled the precise manipulation of neuronal circuits in living tissue.

In this talk, I will introduce methods for tailoring infrared laser beams through wavefront modulation and temporal shaping of femtosecond pulses, allowing targeted excitation of single or multiple neurons within large volumes, deep inside scattering tissue. I will then highlight recent advances aimed at improving the speed and efficiency of neuronal activity manipulation, achieving kilohertz-rate interrogation of large neuronal populations. Finally, I will showcase applications of these approaches, focusing on in vivo mapping of neuronal connections, as a step toward fully optical interrogation of brain structure and function.

This work presents an integrated, high-throughput microscope on a

chip designed for rapid and automated circulating tumor cells imaging based on

cytomorphological features. The system employs a modified time-stretch imag-

ing technique, utilizing a single nanosecond laser pulse split into a sequence of

temporally and spatially separated pulses to illuminate the whole cell at different

moments. Fabricated using femtosecond laser micromachining, the device inte-

grates optical circuits, delay lines, and a microfluidic chip, enabling high-speed

image acquisition with a single-pixel detector. The system is validated using

calibration beads and tumor cells, demonstrating high resolution and stability.

Fully compatible with machine learning algorithms, this platform represents a

scalable, cost-effective solution for advancing real-time liquid biopsy and can-

cer diagnostics.

OptoRheo is a new microscopy platform that allows for live imaging of cells in 3D cultures over long-time courses, combined with micromechanical sensing of the material local to the cells. This is achieved by combining light sheet microscopy, multiplane imaging, optical trapping, and passive particle tracking micro-rheology in a single optical platform. A novel light sheet configuration allows cells to remain undisturbed during imaging, with no dipping objectives or sample scanning involved, allowing delicate samples to grow on the microscope stage over several days. This talk will demonstrate the capabilities of OptoRheo by studying two different cell culture systems, cell cultures grown in hydrogel and spheroid samples.

Wide-field imaging Mueller polarimetry has already demonstrated its potential for the accurate, non-contact, and cost-effective optical diagnosis of tissue in such diverse fields as gastroenterology, gynaecology, obstetrics, neurosurgery and digital histology. The recent developments and perspectives on translating this technique to clinics will be discussed, as well as the additional possibilities for health risks identification and management.

Fast and sensitive detector arrays make Image Scanning Microscopy (ISM) the natural successor of

confocal microscopy. Indeed, ISM enables super-resolution at an excellent signal-to-noise ratio. Optimizing

photon collection requires large detectors and so more out-of-focus light is collected. Nonetheless, the ISM

dataset inherently contains information on the axial position of the fluorescence emitters. We exploit such information

to directly invert the corresponding physical model with s2ISM, a maximum-likelihood algorithm

that reassigns the signal in the three dimensions, improving the signal-to-background ratio (SBR) and resolution.

Those kinds of algorithms show semi-convergent behaviour concerning the loss function of the problem

along the iteration routine. We regularize our s2ISM algorithm through inherent end deep-learning denoisers,

letting users analyze data with SNR levels that before were deemed to be unuseful in specimen structure or

dynamic revealings.

We present a maximum-likelihood estimation (MLE) framework tailored to event-driven detectors to perform computational image reconstruction and phase retrieval. Using Poissonian photon statistics, we built an event-based loss function that maximizes the probability of having the set of events and non-events given the initial parameters. Our loss function can be utilized in both optical and electron ptychography. We demonstrate experimental reconstructions using data acquired with a Timepix3 detector.

We apply the phase triplicator profile to a phase-only hologram to generate three equally intense harmonic orders, yielding a direct version and an inverted complex conjugated version of the target pattern in the ±1st orders, and a delta function in the DC zeroth order. When combined with another identical phase-only target function, the resulting hologram yields convolution and correlation in the ±1st orders, and the target function in the zero-order. Experimental results obtained with a high-resolution liquid-crystal phase-only spatial light modulator (SLM) demonstrate the proposed design.

Since typical reflectivity studies collect intensities, we initiate 2D position-resolved interferometry to obtain phase. On gold pads and thin 3D opal photonic crystals we obtain reproducible phase steps, revealing steps even between different crystal orientations.

We demonstrate an efficient approach for correcting spatially varying (anisoplanatic) aberrations in digital holographic imaging by leveraging a Zernike-Fourier domain representation. The imaging operator was modelled in a matrix form as a combination of Fourier basis functions and Zernike decomposed field-dependent wavefront aberrations. The single-step matrix multiplication greatly reduces computational complexity compared to traditionally relying on explicit matrix inversion or point-wise convolution.

A new class of partially coherent light sources characterized by a cross-spectral density (CSD) function that depends only on a single complex variable has been recently introduced. It has been shown that the CSD of these sources is expandable in power series in their convergence domain and has vortex fields as modes. This enables the generation of a virtually unlimited number of source models with specific coherence structures. In this work, the propagation in the Fresnel region of the field radiated by uni-variable sources is analyzed. Several examples are developed to show the rich variety of behaviors that can be found.

Optical vortices are of interest in the infrared range for applications in the fields of optical fiber communications and femtosecond laser pulses. Among the current techniques used to generate optical vortices, the use of a Spatial Light Modulator (SLM) stands out. However, SLMs are expensive devices, they present a low damage threshold and do not allow the development of compact systems. A solution to this is to record a Holographic Optical Element (HOE) with the interference of two beams, one of them carrying an optical vortex. Available holographic recording materials, such as photopolymer and dichromated gelatin, are only sensitive to visible light. Thus, the recording parameters need to be optimized for reconstruction with a different wavelength. In this contribution, we explore the use of HOEs to generate optical vortices with infrared light, and present experimental results with commercial recording materials that validate the viability of the method.

Experiments whose data are processed using a computational model are often plagued by uncertainties in the experiment which prohibit accurate outcomes of the model. As a result, experimental physicists spend their time in labs painstakingly calibrating their setups to minimize all forms of inaccuracy in the modeling. Although accurate calibration is preferable, in many cases it may be possible to instead include these uncertainties into the modeling. Traditionally this would require some theoretical work to find a suitable optimization approach, which may be just as time-intensive as calibration. In this presentation we will see that automatic differentiation based gradient descent can provide a flexible means of computational optimization, since no manual derivation of gradients is required. We show this approach works well for the case of optimization of the tilt angle in extreme ultraviolet EUV reflection ptychography, where it is able to reliably converge, reduce reconstruction artifacts and improve reconstruction fidelity.

Strong coupling between light and molecular matter is currently attracting interest both in chemistry and physics, in the fast-growing field of molecular polaritonics. The large near-field enhancement of the electric field of plasmonic surfaces and their high tunability make arrays of metallic nanoparticles an interesting platform to achieve and control strong coupling. Two dimensional plasmonic arrays with several nanoparticles per unit cell and crystalline symmetries can host topological edge and corner states. Here we explore the coupling of molecular materials to these edge states using a coupled-dipole framework including long-range interactions. We study both the weak and strong coupling regimes and demonstrate that coupling to topological edge states can be employed to enhance highly-directional long-range energy transfer between molecules.

Organic materials have emerged as promising candidates for light-harvesting applications across the infrared to visible spectrum. Their strong excitonic binding energies and large transition dipole moments enable strong light-matter coupling, with some systems reaching the ultrastrong coupling regime. Meanwhile, two-dimensional (2D) materials exhibit high exciton stability and strong electron–hole interactions due to reduced screening. Here, we present a microscopic model describing the interaction of 2D materials and organic molecular aggregates in an optical cavity. We predict the formation of a hybrid Wannier-Mott-Frenkel exciton-polariton with an enhanced Rabi splitting, exceeding that of the pure organic cavity by several tens of meV. As an example, we examine a cavity with 2D tungsten disulfide and a cyanine dye, where this enhancement reaches 5%. The complementary characteristics of Wannier–Mott and Frenkel excitons enable tunable polariton states that merge into a single hybrid state as a function of detuning, supporting dual Rabi splitting mechanisms. This hybrid system offers a versatile platform for exploring quantum optical phenomena in both strong and ultrastrong coupling regimes.

In this work we study the topology of the bands of a plasmonic crystal composed of graphene and of a metallic grating. First, we derive a Kronig–Penney type of equation for the plasmonic bands as function of the Bloch wavevector and discuss the propagation of the surface plasmon polaritons on the polaritonic crystal using a transfer-matrix approach. Second, we reformulate the problem as a tight-binding model that resembles the Su–Schrieffer–Heeger (SSH) Hamiltonian. In possession of the tight-binding equations it is a simple task to determine the topology of the bands. This allows to determine the existense or absence of topological end modes in the system. Similarly to the SSH model, we show that there is a tunable parameter that induces topological phase transitions from trivial to non-trivial. In our case, it is the distance 'd' between the graphene sheet and the metallic grating. We note that d is a parameter that can be easily tuned experimentally simply by controlling the thickness of the spacer between the grating and the graphene sheet. It is then experimentally feasible to engineer devices with the required topological properties. Finally, we suggest a scattering experiment allowing the observation of the topological states.

We investigated a set of films composed by zinc-phtalocyanine (Zn-Pc) dispersed into a poly-methyl methacrylate (PMMA) matrix, to evaluate the radiative cooling performance through the two infrared transparency windows of IR radiation in the atmosphere. ZnPc present strong and accentuated absorption bands in both visible and infrared range and can dissipate energy by radiating in the infrared band. We will firstly describe the process of samples preparation. Afterwards, we will introduce the experimental setup employed for linear optical characterization in the infrared range along with the obtained experimental results. Finally, we will give details about the numerical model that we developed in order to evaluate the radiative cooling effectiveness of the different films.

Radiative cooling is a passive cooling strategy that enables heat dissipation into space through thermal emission in the atmospheric transparency windows (3–5 µm and 8–13 µm), helping to mitigate global warming. In this study, a cost-effective and free standing SBS@TiO₂NPs-MPTMS composite was designed by incorporating 25 nm anatase-phase TiO2NPs, functionalized with 3-(mercaptopropyl)trimethoxysilane (MPTMS), into a styrene-butadiene-styrene (SBS) copolymer matrix. First, several reaction parameters were optimized to achieve well-dispersed TiO₂NPs-MPTMS. Then, composites films containing 1%, 5%, 7% weight percent of TiO₂NPs-MPTMS were prepared and characterized by mid-infrared reflectance spectroscopy (1.6–25 µm). Results showed improved radiative cooling performance with increasing nanoparticle content, evaluated through a quality factor based on emissivity within the atmospheric windows. These findings confirm the potential of SBS-based composites for efficient passive cooling applications.

We report on the lithography-free fabrication of planar cavity-type metasurfaces based on phase-change materials. Multispectral images can be recorded on the presented metasurfaces. This provides a promising platform for optical security and information encryption

The ARTEMIS project aims to develop integrable quantum sources based on metal-organic compounds with transition metal and/or lanthanide ions. These materials exhibit tunable linear emission and nonlinear optical properties, enabling on-demand generation of single photons and entangled photon pairs or triplets. When integrated with plasmonic supernanostructured cavities, these molecular emitters achieve strong optical enhancement. Our group focuses on the quantum characterisation of the light emitted by these sources to explore their potential for new metrology and sensing applications in the quantum regime. Spectroscopic and time-resolved measurements on newly synthesized compounds Tb−N(Bzlm)3 and Eu−N(Bzlm)3 dissovled in DMSO at high concentration reveal narrow emission bands and relatively long decay times.

Fluorohafnate glasses (HfF4–BaF2–LaF3–AlF3–NaF) doped with erbium ions were fabricated by the melt-quenching technique at 870 °C in argon atmosphere, and their spectroscopic properties were studied. The glasses exhibit a low phonon energy (575 cm-1), a broadband mid-infrared emission (stimulated-emission cross-section: 0.51×10-20 cm2 at 2.76 µm), and long luminescence lifetimes of the 4I11/2 and 4I13/2 manifolds making them attractive for 2.8-µm laser sources.

In this study, we investigate the optical scattering properties of self-assembled MoS₂ nanostripes produced by solid precursor film chemical vapor deposition. Employing multiple two-dimensional Finite-Difference Time-Domain (FDTD) simulations with randomly varying parameters, we evaluated far-field scattering behaviors, achieving strong agreement with experimental observations. Our findings emphasize the significant role of intrinsic structural disorder in practical MoS₂-based photonic applications, demonstrating how controlled structural defects substantially impact optical performance.

Hafnium oxide (HfO₂) is of increasing interest in both microelectronics and photonics due to its favorable optical and dielectric properties. In particular, its high refractive index, wide bandgap, and chemical stability render it attractive for optical coatings and metasurfaces down to the ultraviolet spectral range. Atomic layer deposition (ALD) has been commonly employed to produce high-quality HfO₂ films. In this contribution we are reporting on the measured refractive index from a wavelength of 120 nm to 600 nm.

The development of sensors for ultraviolet (UV) radiation with inherent insensitivity to visible light, commonly referred to as 'visible-blind' UV detectors, holds paramount importance across a spectrum of advanced technological applications. Such sensors offer enhanced signal-to-noise ratios by eliminating interference from ambient visible light, crucial for precise detection in fields like flame detection, UV astronomy, and cultural heritage. In this regard, heterojunctions based on wide bandgap semiconductors, such as Ga2O3, present challenges in the production of large-area devices, limiting their implementation in systems requiring extensive detection areas. The need for efficient and scalable 'visible-blind' UV sensors drives the exploration of alternative materials and architectures. In this framework, we show the potentiality of Eu3+-based luminescent materials, usually employed as Luminescent Solar Concentrators, in the detection of UV photons.

We present advances in lithium niobate (LN) photonics for reservoir computing applications. Our dry-etch process achieves 2.5 µm features with sub-10 nm roughness despite lithium fluoride byproduct challenges. While LN platforms exist for time-delay computing, we explore LN as an interconnecting matrix for spatio-temporal reservoir systems. Our approach inscribes optimized phase values through etching, leveraging LN’s nonlinearities to enhance computational performance—demonstrating LN’s advantages.

We studied space-charge waves caused by the competition between holes and electrons in an undoped Bi12TiO20 photorefractive crystal and generated during holographic recording with a 532 nm wavelength laser light and the reflection geometry. A non-linear relation between the velocity of the resonant space-charge waves and light intensity, as well as the photovoltaic effect, is demonstrated. The experimental data is in good agreement with the theoretical model reported here.

Being one of the most important tools in industrial and medical fields, the red-NIR laser has caught much attention in research studies. To enhance the emitting intensity of the red-NIR laser generation from Er3+ ions inserted into a glass network, the effect of Yb3+, Nd3+, and Ce3+ ions on the emitted laser beam was studied. First, a host glass network of 44P2O5-15ZnO-10Pb3O4-15NaF-15MgF2-1Er2O3 (PZPbNMEr³⁺) was proposed as a red-NIR lasing material and was reinforced by 0.5 and 1 mol% of Yb3+, Nd3+, or Ce3+ ions. XRD, density, FTIR, and Raman spectra examined the structural variations resulting from compositional changes, which showed increased glass network tightness. The glass tightness was positively reflected in the thermal stability and elasticity of the considered glasses, reflecting their suitability as lasing media. Optically, all the distinctive absorption bands of the Er3+, Yb3+, Nd3+, and Ce3+ ions appeared in the optical absorption spectra in the 200–2500 nm region. A significant impact of the induced strain or crystal field of the added RE3+ ions was also observed on the optical properties.

This study investigates the surface characteristics of copper plating machined with a single-crystal diamond tool. The surface topographies of the machined samples were evaluated using WLI and AFM. PSD analysis showed that copper plating is smoother than oxygen-free copper at spatial frequencies below 2 × 10⁴ mm⁻¹. Although the PSD of copper plating was the highest above 2 × 10⁴ mm⁻¹ due to its sand-like texture, this did not significantly affect its RMS roughness. Microstructural analysis using EBSD and XRD revealed that the copper-plated surface consists of fine crystalline grains, likely responsible for the observed texture. These results indicate that copper plating can be smoothly machined and is suitable for use in optical components.

On-chip microfluidic devices have gained significant attention for their unique wettability properties. In this study, we developed a microfluidic chip by laser treatment of GPOSS-PDMS polymer film, achieving wettability variations influenced by specific ablation parameters.

Abstract

BaTiO3 is a promising candidate for multi-functional memristive devices with high resistance contrast between ON and OFF states. Doping, as well as native-defect tuning, plays a critical role in the modulation of resistive switching. Herein, a systematic density functional theory (DFT) based studies have been performed to understand the electronic properties of vacancy-induced and doped BaTiO3 systems for optoelectronic applications. DFT calculations have been performed on various possible vacancies and doping on B-sites of BaTiO3 to further confirm the presence of defect states. Partial density of states (PDOS) has been calculated in the case of vacancy-induced BaTiO3, and it is clearly observed that the electronic band gap arises due to the change in the overlapping of O-2p and Ti-3d orbitals, suggesting re-hybridization between these two orbitals. By analyzing the density of states (DOS), charge density, and formation energy calculations reveals the enhancement in the electronic properties after the inclusion of native defects. The present study reveals that a theoretical approach can be used to probe the defect states of systems like perovskites and transition metal oxides.

Aluminum oxide (Al₂O₃), widely known as alumina, is a technologically important material due to its excellent thermal stability, wide bandgap, and optical transparency. In this study, we present a comprehensive theoretical investigation of the structural, electronic, and optical properties of Al₂O₃ using first-principles density functional theory (DFT). The calculations were performed for the stable α-phase of Al₂O₃ (corundum structure), with geometry optimizations confirming experimental lattice parameters. The electronic band structure reveals an indirect bandgap, with a calculated value of approximately ~6.2 eV using the PBE functional, and corrected to ~8.8 eV using the hybrid HSE06 functional to match experimental observations. The density of states indicates that the valence band is predominantly composed of oxygen 2p states, while the conduction band is mainly derived from aluminum 3s and 3p orbitals. Optical property simulations, including the complex dielectric function, absorption coefficient, and refractive index, demonstrate that Al₂O₃ is optically transparent in the visible region and exhibits significant absorption only in the deep UV range. These findings highlight the suitability of Al₂O₃ as a high-k dielectric material and optical coating in next-generation optoelectronic and photonic devices.

Cryogenic single-molecule localization microscopy (cryo-SMLM) enhances photon output and structural preservation but is limited by the lack of fluorophores that blink intrinsically at low temperatures. We demonstrate that nanographene dibenzo[hi,st]ovalene (DBOV) exhibits spontaneous blinking at 91 K, overcoming the need for conventional dyes that depend on liquid buffers. Analysis of intensity time traces yields an average on-state duration of 493 ms and an on-off ratio of 0.043, indicating DBOV’s promise for enabling SMLM at cryogenic temperatures.

Live imaging of 3D cellular cultures, such as organoids, remains a challenging task due to the complexity of acquiring fast volumetric data over the size of the organoid as well as the difficult optical conditions imposed by the matrigel or scaffolds. These support structures, commonly used in organotypic cultures, don't offer properties favourable to imaging as they are typically opaque at visible wavelengths and may poses auto-florescence. This, ultimately, leads to a degradation of image quality and loss of signal-to-noise ratio.

In this work, we present a novel oblique plane microscope (OPM) aimed at tackling these challenges. In our setup, we bring together adaptive optics techniques, multi-directional illumination, and structured illumination in order to increase the penetration depth of both the detection and excitation beams. Additionally, we implement a recently developed remote refocussing scheme that removes the necessity of secondary and tertiary objectives - commonly used in OPM setups - reducing the cost and technical complexity of the microscope.

Accurate and continuous respiratory and heart rate monitoring is essential during medical procedures to ensure patient safety. This work explores the feasibility of using LPGs for monitoring in clinical environments where immunity to electromagnetic interference is crucial. Preliminary analysis and results suggest the validity of the proposal. Future research will focus on experimental validation and signal processing techniques to enhance performance.

Hexagonal boron nitride (hBN) is emerging as a promising platform for single-molecule biophysics studies due to its favourable combination of structural, chemical and optical properties. It is an atomically smooth and inert 2D material that is optically transparent, and which enables studies of biomolecule dynamics in 2D confinements at the single-molecule level [1]. In this work we show that ATTO647N-labelled ssDNA structures immobilized on a coverslip underneath hBN flakes can be imaged with TIRF microscopy with single-molecule resolution and retain their emissive properties. We compare the photophysics of the fluorophores in buffer, in air and under hBN coverage, and find that the hBN coverage decreases the photo switching rate compared to Atto647N exposed to ambient conditions. The ON-time and intensity before bleaching of the fluorophores shows a decrease compared to those in buffer and varies as a function of the hBN thickness. We ascribe this to the presence of lattice defects in the hBN, which can exchange energy with the fluorophores. The arrangement of the dyes can be accurately imaged, showing promise of this platform as a single-molecule FRET platform for surface-based biosensing.

[1] Diffusion of DNA on Atomically Flat 2D Material Surfaces, Dong Hoon Shin, et.al., bioRxiv 2023.11.01.565159; https://doi.org/10.1101/2023.11.01.565159

Femtosecond laser micromachining (FLM) has emerged as a power-

ful technique for the precise fabrication of optical components, enabling high-

resolution structuring in transparent materials such as fused silica and borosil-

icate glass. The nonlinear absorption mechanisms involved allow for localized

modifications at the microscale with minimal thermal effects. In this work, we

demonstrate the application of FLM for the fabrication of integrated optical

beam splitters and microlenses. By carefully controlling laser parameters and

subsequent post-processing steps, we achieve structures with high optical qual-

ity and functional performance. The results demonstrate the potential of fem-

tosecond laser technology in integrating complex optical components, opening

new possibilities for the development of lab-on-chip systems.

Single-molecule detection is crucial for probing molecular interactions, but weak fluorescence signals and the risk of photodamage from high laser intensities limit current approaches. Conventional enhancement methods often require dried samples or introduce compatibility issues, making them unsuitable for dynamic, in-solution measurements. We present a hybrid platform that combines photonic crystals (PhCs) with hexagonal boron nitride (hBN), which provides an effective surface for constraining single-stranded DNA (ssDNA), allowing vertical immobilization while preserving lateral mobility. Simulations show a 218-fold increase in electric field intensity at the hBN surface, enabling significantly brighter fluorescence without increasing laser power. This localized enhancement reduces the risk of photodamage by minimizing overall light exposure. The platform maintains label compatibility and molecular mobility, offering a scalable and biocompatible solution for real-time single-molecule tracking and high-sensitivity biosensing.

We describe the rules to enhanced the Brillouin interaction in silica nanofiber.

We report a focused optical vortex array (FOVA) generator prepared by printing a Dammann spiral zone plate on the composite fiber facet using femtosecond laser two-photon polymerization. The generation of FOVA is verified by simulation and experiment. The all fiber generator of FOVA exhibits high flexibility and compactness, making it a suitable candidate for applications in fields such as optical manipulation and optical communications.

Polarization-maintaining properties for a nested tube negative curvature hollow-core fiber are numerically investigated when the whole fiber cross-section is subjected to physical deformation leading to elliptical fiber forms. The results indicate that ellipticity provides a useful fine-tuning mechanism for polarization maintaining operation of fiber.

Accurate displacement measurement is critical in areas such as structural health monitoring, bioengineering, and industrial or high-radiation environments. Optical fiber microdisplacement sensors offer significant advantages for these applications, including high precision, reliability, compact size, and flexibility. Their ability to operate under extreme conditions such as elevated temperatures, corrosive atmospheres, or high-pressure environments makes them ideal for integration into complex or confined systems.

This work presents the experimental analysis of single-mode optical fibers (SMFs) modified with transverse through-hole microchannels, fabricated using femtosecond laser processing combined with ultrafast laser-assisted etching. These structures have been experimentally demonstrated as micro-displacement sensing devices.

Pulsed laser synthesis (PLS) of nanomaterials in liquids is a promising technique for synthesizing high-purity nanoparticles. However, its industrial scalability is limited by low production rates. This contribution discusses strategies to enhance nanoparticle yield as accurate control of the temporal dispersion and spatial beam shaping. Additionally, we explore applications of PLS-derived nanoparticles.

3D Stereolithography (SLA) technologies have emerged as a novel methodology to create a wide range of structures in the millimetric scale. Nevertheless, advancements in fields such as microfluidics or medicine rely on the creation of structures featuring micrometric resolution. SLA encounters resolution limits when printing objects within this range of sizes, especially when requiring hollow structures. On its side, femtosecond (fs) laser ablation emerges as a technique overcoming these limitations. The non-linear phenomena involved in the fs laser-matter interaction enable to perform a neat and precise extraction of material, resulting in a laser writing featuring microns. We propose a hybrid approach combining SLA and fs laser ablation to create a multi chamber microfluidic chip where micrometric substructures enable an accurate confinement of the samples.

Green and blue lasers have seen increased use in manufacturing of copper. They offer great advantages compared to common IR lasers especially in additive manufacturing. We tested the feasibility of a low average power femtosecond lasers at a centre wavelength of 515nm for use in micron-precision additive manufacturing of copper particles. A laser beam with an average power of 4W in the near IR was used to achieve second harmonic generation, and the resulting green beam was used to melt copper particles with sizes between 30 and 50µm. Melting of the powder was achieved and small two-dimensional structures were created.

We present a novel near-infrared broadband, flat-top optical

frequency comb spanning 1.6 THz. This comb is generated using an

interband gain medium operated in an ultrafast gain recovery regime within

a unidirectional ring cavity. The remarkable stability of our approach is

evidenced by a 1 Hz RF linewidth. The injected RF signal not only governs

the spectral bandwidth and free spectral range but also tailors the comb’s

spectral shape—a feat achieved by simultaneously injecting multiple

modulation tones. This advanced level of control opens promising avenues

for applications in communication, sensing, and ranging, where precise and

stable frequency lines are essential for performance and reliability

Our work centers on the question how you can use far field diffraction of light to read out or reconstruct sub-nanometer spatial information as relevant for, e.g., metrology in nanofabrication processes, given that you are at the same time free to design a nanophotonic scattering target, free to program the incident wavefront, and able to angle-resolve diffraction patterns over a high NA. We use resonant multiple scattering motifs borrowed from the field of dielectric and Fano-resonant metasurfaces, which provide strong scattering resonances with both strong near fields and characteristic far fields. I will discuss both linear scattering experiments, and experiments in which we measure third harmonic generation diffraction pattterns. The experiments elucidate how metasurface resonances and their interferences optimally transduce tiny near-field perturbations into far field information.

In optical metrology, Fisher information is a central metric that

quantifies the precision that can be achieved in a measurement. For coherent

light, it has been shown that the Fisher information can be written as a Hermi-

tian operator using the scattering matrix of the system. The maximum eigen-

states of this operator are the incident light fields that give the largest possible

Fisher information and therefore give the most precise measurements. Here,

we extend the operator to multiple parameters, representing Fisher information

as a matrix. The measurement precision is related to the inverse of this matrix

by the Cramér-Rao bound, however optimizing the inverse matrix is not trivial.

We consider several scalar functions of this matrix in order to optimize for all

parameters simultaneously, and then corroborate our findings using a scattering

system comprised of coupled dipoles in 2D.

Many researchers consider AI too unreliable for scientific use, but with Simulation Based Inference (SBI) we present a class of ML models that produce comprehensible results that adhere to the high statistical standards of conventional publications. In SBI, the model is trained on simulated samples, which allows the scientist to exert full control over the learned features and only requires to usually much simpler forward measuring process. After the training, the model is used to solve the inverse problem of finding the best parameters given an experimental data point with its variance purely based on the relations defined in the simulator. We present a novel model architecture for the application in nanoimaging and investigate the performance of the method for practical metrology applications.

Artificial neural networks (ANNs) have emerged as powerful tools for imaging through complex scattering media, where conventional approaches fail due to dynamic and unpredictable light propagation. However, the fundamental limits of such ANN-based imaging systems remain largely unexplored. We present a model-free approach to estimate the Cramér-Rao bound (CRB), which sets the ultimate precision limit for parameter estimation, and apply it to evaluate the accuracy of the ANNs trained for imaging through complex scattering media. We compare how well various ANN architectures can localize a reflective target obscured by dynamic scattering. Our approach addresses high-dimensional, non-Gaussian, and correlated data using principal and independent component analysis combined with non-parametric density estimation. Comparing several ANN architectures, we find that convolutional networks with coordinate-aware layers can approach the CRB, achieving near-optimal localization performance. This method provides a general benchmarking tool to assess and guide the design of deep-learning-based imaging systems and opens an opportunity for precision metrology in complex and disordered environments.

In this work, we experimentally demonstrate new types of hybrid supercell metasurfaces that exploit different types of supercells and unit cells in the same design, creating a smooth transition between them. We use this new method to control the phase and amplitude of light at the same time while designing speckle-free holograms.

Studies on individual nano-emitters offer fundamental insights into their spectral properties and emission characteristics. The signal intensity of e.g. dye molecules in fluorescence assays can be improved by coupling them to plasmonic nano-antennas. The properties of the hybrid system crucially depend on the specific position of the emitter relative to the antenna, which however cannot be resolved by conventional microscopy. An approach is demonstrated that uses nanocones as the antennas and point-spread function deformations for localization determination. Intensity time traces are investigated to study binding statistics, location-dependent enhancement factors and fluorescence reshaping.

The objective of this work is to study the effects of plasmonic

nanoparticle arrays on the emission of organic semiconductors used for

OLEDs. As a first step, we report the investigation of the response of Agbased arrays in various configurations in terms of geometry and structure.

Metamaterials are artificially structured media offering multiple applications. Among them, epsilon-near-zero (ENZ) metamaterials are a platform for enhanced nonlinear optical phenomena. Multilayer hyperbolic metamaterials (MHMs) belong to the latter class and are tailorable structures for the study of the optical Kerr effect (OKE). In this work, different ENZ Au/SiN MHMs are crafted, their OKE parameters are spectrally characterized, and the nonlinear response temporal dynamics is studied.

Amorphous silicon carbide offers unique properties for the optimiza-

tion of microstructured optical elements. We present a study on the technologi-

cal processing, the resulting material properties as well as potential applications.

Persistent phosphors, especially in nanophosphor form, are valued for their long-lasting afterglow and are promising for applications like anticounterfeiting, data storage, and imaging displays. However, their use is limited by challenges in tuning their properties and low energy storage capacity. This work introduces a novel transversal strategy to enhance persistent luminescence in nanophosphor thin films by modifying their optical environment without changing their composition. Using the sol-gel method, we fabricated layered garnet films with time-dependent chromaticity and developed transparent ZnGa₂O₄:Cr³⁺ films embedded with TiO₂-based scattering centers. This design led to a 3.5-fold increase in afterglow intensity and faster charging, thanks to enhanced light absorption and improved outcoupling. This approach demonstrates a powerful and versatile way to optimize persistent nanophosphors, opening new opportunities for creating advanced coatings with dynamic luminescent properties, particularly for high-performance anticounterfeiting applications.

We propose an efficient method of mitigating Stimulated Brillouin Scattering in a single-frequency multimode fiber amplifier. By applying wavefront shaping to the continuous wave seed, we excite many modes in our Yb-doped multimode fiber amplifier reducing the backward propagating Stokes power. Simultaneously, we can control the output profile ensuring good beam quality. In the experiment, our multimode fiber amplifier achieves 503~W amplified signal power, its slope efficiency is 82~\%, the amplified signal has 18~kHz spectral linewidth and the propagation factor of the output beam is less than 1.35.

We present measurements of the evolution of the core and cladding diameters in tapered silica microfibers by LC-OCT. The results will help to refine the models of propagation of modes in tapers.

We report the observation of classical light thermalization to the negative tem-

perature Rayleigh-Jeans (RJ) equilibrium states. We extend theoretically these

equilibrium states to the Bose-Einstein quantum regime (BE) through the anal-

ysis of the thermodynamic properties.

We demonstrate a building block validation strategy for structural health monitoring (SHM) of aerospace composite structures using optical fibre Bragg grating (FBG) sensors. Standard FBGs are surface-mounted for global strain monitoring, while microstructured FBGs (MOFBGs) are embedded to resolve directional and through-thickness strain. We validate this approach from coupon to fuselage scale. The sensors detect impact-induced damage, and their outputs are fused into a Global Damage Index (GDI) that quantifies structural integrity. We show that the sensor technologies and damage evaluation methods scale effectively across component size and complexity, offering a certified path toward embedded SHM in aerospace composites.

In this work, a switchable multiwavelength L-band fiber ring laser based on a polarization-dependent booster optical amplifier (BOA) and a motorized polarization controller is experimentally demonstrated. Lasing wavelengths selection is achieved by automatically adjusting the polarization state, enabling single, dual, or triple line emission.

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Extending single-photon detection capabilities into the mid-infrared is expected to have far-reaching implications for long-wavelength quantum optics, quantum and free-space communication, astronomy, environmental monitoring, and fundamental molecular sciences. We showcase the development of short-wave infrared (2.2-2.3 µm) and mid-wave infrared (3.0 µm) superconducting nanowire single-photon detectors (SNSPDs). In both wavelength ranges, we venture beyond state-of-the-art and achieve the best-reported system detection efficiencies and specific detectivity. We discuss the challenges in cryogenics, optics, and SNSPD design and use our mid-infrared single-photon detection to characterize emerging materials platforms and quantum emitters in a previously unattainable manner.

There is a growing interest in infrared technology for surveillance, military and space applications. Designs in infrared waveband have evolved taking advantage of new detector developments. New generation of High-Definition detectors allow for better performance and resolution. The increase in image field height, implies new challenges for designers to achieve aberration correction and unwanted light control. The need to use different fields of view and a rapid response to switch between different FOVs, increases the interest for continuous zoom in infrared. In such systems it is a significant challenge to control the parameters previously mentioned for all zoom positions. This paper presents a compact 10:1 optical zoom, with focal lengths from 20 to 200mm, F#2.8 in the 3.6-4.2µm waveband, with a 1280x1024 pixels, pixel pitch 7.5 µm cooled detector. The design consists in seven lenses. The optical system is able to focus at 25m near distance for SNFOV and 10m for WFOV. Athermalization ranging from -40ºC to 70ºC is achieved with an active focusing lens system.

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We present a fully quantitative full-field optical coherence tomography realized in transmission. This method allows, for the first time, a direct and fast retrieval of the complex amplitude of light that propagated through the sample of interest. We show that with an appropriate spectral range of the swept-source laser, this method separates weakly-scattered photons from the multiply-scattered ones, thus allowing measurement of thick and scattering samples, like tissue slices or organoids. With a relatively easy optical setup and straightforward numerical processing, this method is superior to classical quantitative phase imaging methods like digital holographic microscopy.

Interferometers for displacement measurement with picometer resolution are required. The main cause of degradation of interferometer resolution is air fluctuation. To investigate the effect of air fluctuation on displacement resolution, we have developed a sinusoidal phase modulation interferometer capable of measuring 1D displacement with 10 picometer resolution and 2D in-plane displacement (air fluctuation). The interferometer is of Michelson type with different polarizations in the reference and measurement arms. By exchanging the phase-modulated electro-optical modulator and photodetector of this interferometer, 1D and 2D in-plane displacements can be measured, respectively.

We propose a maximum-likelihood estimation (MLE) framework tailored to event-driven detectors, such as Timepix3, to perform computational image reconstruction from event trigger data. Unlike frame-based acquisitions, which aggregate intensities over an exposure period, event-driven cameras asynchronously record time-of-arrival data whenever a pixel exceeds a photon-count threshold. Our approach models the Poissonian probability of photon arrivals and incorporates both triggered (event) and untriggered (non-event) pixels into a unified log-likelihood function that remains well-defined across low-dose and saturation regimes. This naturally addresses challenges such as imaging under scarce photon conditions and pixel saturation in a consistent manner. Using gradient-based optimization, this MLE framework can be applied to several computational imaging techniques such as ptychography or coherent diffraction imaging.

Iterative reconstruction algorithms are commonly employed in in-line digital holography to retrieve phase information from one or more intensity images. The methods rely on iterative propagation of the complex wavefront between the measurement and reconstruction planes. To address the ill-posed nature of the reconstruction problem, constraints are applied in each plane. Despite yielding quantitative phase information, these approaches ignore aberrations introduced by the optical system. We propose a straightforward extension to these iterative algorithms to account for these aberrations, modelled here as a complex point spread function (PSF). Because the PSF can vary across the field of view, two scenarios have been investigated: one accounting for PSF variation and one ignoring it. With equal computational cost for convolution, and hence reconstruction time, the proposed method improves the accuracy of aberrated holograms reconstructions.

In this presentation, the aluminium oxide integrated photonics platform will be presented, as well as some examples on how it can enable next generation quantum technology.

Modulated free electrons are emerging as powerful tools in quantum science, offering exceptional spatial, spectral, and temporal resolution. Beyond their role as high-precision probes, recent advances have highlighted their potential for quantum control, enabling coherent manipulation of light–matter systems. In this work, we explore how the quantum degrees of freedom of modulated electron wavepackets can be harnessed for both preparation and readout of quantum states in targets ranging from single quantum emitters to hybrid polaritonic systems. For quantum emitters, we show that periodic electron combs induce Rabi-like dynamics without entanglement, preserving state purity. We identify regimes where realistic modulations retain this behavior, enabling robust state preparation, and propose a protocol for full density matrix reconstruction that relies on the electron's coherence. We then extend our analysis to polaritonic targets, revealing how modulated electrons coherently interact with their complex excitation landscape. This enables both spectral probing via techniques like electron-energy-loss and cathodoluminescence spectroscopy, and active quantum control in the strong-coupling regime. These results position modulated electrons as versatile quantum resources for probing and controlling a broad range of light–matter platforms.

Group-IV colour centres in diamond, such as tin-vacancy (SnV) centres, are emerging candidates for quantum technologies [1]. Especially with their inversion-symmetric crystallographic structure, providing excellent optical characteristics [2], resilience to electrical noise, and an efficient spin-photon interface with narrow zero-phonon-line (ZPL) emission [3]. However, ion implantation significantly damages the diamond lattice [4], requiring annealing to restore crystallinity and activate the colour centres [5]. Femtosecond laser annealing is an emerging technique for enhancing the activation yield; however, with ultrashort and high-intensity pulse irradiation, diamond-to-graphite transformation is reported to be more likely under such non-thermal heating mechanisms [8]. Both high-fluence blanket-implanted and single-ion-implanted diamond samples are annealed by laser treatment of unfocused femtosecond laser pulses at 400 and 800 nm wavelengths, 60 fs pulse duration, 1.4 kHz pulse repetition rate, and varying multi-pulse fluence values. Two-dimensional photoluminescence scans, photoluminescence spectrum, Raman spectroscopy, and optically detected magnetic resonance (ODMR) measurements are being used to evaluate activation efficiency. To validate the experimental results, we are also exploring and developing a two-temperature model (TTM) [9] with COMSOL Multiphysics ® to simulate the energy exchange between electron and lattice subsystems isolated under ultrashort pulse irradiation [10].

Mid-infrared sensor technology plays an increasingly important role in modern biodiagnostics, in particular in (pre)clinical screening and monitoring scenarios. Non-invasive exhaled breath analysis based on mid-infrared (MIR; 3-20 µm) photonics ranges among the most flexible sensing solutions for addressing molecular constituents and biomarkers within the exhaled breath matrix. In particular, with the emergence of quantum and interband cascade laser (QCL, ICL) technology along with interband cascade LEDs (IC-LEDs) along with

advanced waveguide concepts such as substrate-integrated hollow waveguides (iHWGs) integrated MIR sensing solutions for portable usage are on the horizon. The discussion of latest MIR photonic technologies in this presentation will be augmented by highlight biomedical applications including testing for long-COVID and bacterial infections in exhaled breath underlining the utility of next-generation mid-infrared biophotonics.

We present a four-dimensional (4D) Surface Plasmon Resonance (SPR) Imaging biosensor for real-time, array based high-through biomolecular bindings detection. The sensor measures the sensitive phase change induced spectral colour variation at plasmonic resonance with imaging device. It captures two-dimensional biomolecular bindings signal in the time-domain with spectral colour space information (4D imaging data), while no complex phase extraction is required. In the experiment, measurements for refractive index (RI) samples in 1.3330-1.3455 RIU were performed and the sensor RI resolution was found to be 7.2 x 10-6 RIU. The sensor was further demonstrated for antibodies molecular bindings detection in a 5 x 5 array format and 25 biomolecular binding interactions were monitored in real-time. In on-going works, we apply the imaging biosensor for Monkeypox virus neutralizing antibodies detection, which can contribute to Monkeypox virus vaccination development.

Genetically encoded voltage indicators (GEVIs) allow high-throughput and high-resolution measurements of electrical activity in mammalian cells through membrane voltage modulated fluorescence. Recently, bright, fast and photostable GEVIs have been developed, mostly though directed evolution. However, low voltage sensitivity still severely limits the signal to noise ratio of voltage measurements with GEVIs. This impedes massive parallel recording of membrane voltages and places high demands on imaging hardware. Through rational protein engineering, we have developed a novel rhodopsin-based voltage sensor with a sensitivity of over 200%, far surpassing current state of the art voltage sensors. By optimizing the kinetics of this new sensor, we hope to enable voltage recordings with unprecedented fidelity.

An optical fibre sensor with a long period grating (LPG) is described for the binding protein FKBP12 detection. An ad-hoc synthesized recognition element is immobilised on the fibre surface in correspondence of the LPG by using a home-made microfluidic flow-cell. Measurement is performed by flowing solutions in the flow-cell with increasing FKBP12 concentration and measuring the shift of the LPG resonant peak.

A nanoplasmonic biosensor is presented based on periodic arrays of gold nanoprisms, engineered for high-sensitivity and label-free detection of biomolecular interactions. Integrated within a microfluidic platform, the biosensor is designed to operate under well-controlled culture conditions, enabling real-time analysis of cytokine secretion from live cells. Our system offers superior sensitivity compared to conventional techniques while simplifying the detection workflow by eliminating the need for fluorescent markers. The optical configuration is fully compatible with standard inverted microscopes, making it ideal for widespread adoption in biological laboratories. Furthermore, the compact and modular design facilitates integration into organ-on-chip systems for monitoring the dynamic behaviour of healthy and diseased cells in co-culture environments, paving the way for advanced biomedical research and personalized diagnostics