Conference Agenda

This article presents the manufacturing and application of an additively manufactured tool holder for CNC grinding. The tool holder was produced using material extrusion (MEX) with “316L Ultrafuse” stainless steel filament from BASF, then sintered and machined. The intention of the developed tool holder is to improve coolant distribution on the tool surface. Additive manufacturing allows the geometry of the tool holder to be individually adapted to the specific tool design, enabling an optimized and more uniform distribution of coolant across the surface. In combination with an additively manufactured grinding tool made of hybrid polymer-bonded dimond filament, the tool holder was successfully used in a fine grinding process. A surface roughness of up to Sq = 26 nm was achieved.

This study investigates the optical properties of volume Bragg gratings (VBGs) for wavelength stabilization of high-power diode lasers. An external cavity incorporating a reflective VBG was implemented, and key parameters such as spectral linewidth, wavelength shift, and output power were experimentally evaluated. The results show that the emission wavelength exhibits a linear dependence on drive current with a slope of approximately 1.23 nm/A. The spectral linewidth is significantly reduced from 3.38 nm to below 0.4 nm with VBG feedback. In addition, temperature-induced wavelength drift is suppressed from 0.3 nm/K to 0.01 nm/K. Although optical power losses in the range of 1.3–5.2% are observed depending on VBG reflectivity, the overall results demonstrate that VBG-based stabilization provides substantial spectral improvement with acceptable trade-offs. Simultaneously, Tapered Double Clad Fiber (T-DCF) amplifier test was tried using a similar design 976nm VBG pumping LD.

Volume holography has long been a key area of research, with numerous applications in the field of photonics. In recent years, it has regained significant attention due to the ability of volume holograms to operate under off-axis conditions, enabling applications such as augmented reality, see-through display systems, and optical waveguides. Traditionally, research in volume holography has focused on the diffraction efficiencies of the propagating orders within the hologram. Nevertheless, the phase modulation introduced by the hologram is equally critical for many applications. In this work, we present both amplitude and phase results for volume diffraction gratings, comparing three different approaches: Kogelnik’s Coupled Wave Theory, Beta-Value Coupled Wave Theory, and Rigorous Coupled Wave Theory. Our results show that the Beta-Value Coupled Wave Theory provides better agreement with Rigorous Coupled Wave Theory, indicating that it is the most suitable method for simulating volume holograms using the non-local grating approach.

We present the use of the common path point diffraction interferometry for transparent sampling positioning in two photon polymerization systems. The point diffraction interferometer is built just by including in the optical setup of the two photon polymerization (2PP) system the semi-transparent plate with a 7 microns hole that creates the reference spherical wavefront. This technique allows detection of the front and back surfaces of the transparent substrate with a precision of 5 microns. The technique is simple and costless (just the semi-transparent plate with the pinhole is needed) in comparison to other interferometric techniques based on Mach-Zehnder or Michelson interferometry. It can be seen as a hybrid between interferometric and confocal techniques where the sample can be seen during the positioning procedure.

X-ray lasers on a chip represent a highly anticipated breakthrough in photonics, offering compact and efficient sources for advanced applications. In this work, we take a significant step forward through detailed theoretical characterization of lattice tolerance and gain parameters. Silicon was chosen as the host material to realize an integrated laser-on-a-chip system. Both intrinsic and extrinsic pumping mechanisms were considered. Our analysis indicates that the (111) crystallographic plane is optimal, as it supports the phosphorus fluorescence line, commonly introduced as a dopant in the structure. Importantly, the design leverages a distributed feedback (DFB) mechanism to achieve stable lasing and enhanced spectral selectivity. These results provide a strong theoretical foundation for experimental realization and the future development of chip-scale X-ray lasers.

This study is focused on the ZEMAX OpticStudio design simulation of the Brillouin light scattering (BLS) spectrometer setup based on tandem Fabry‐Perot interferometers. The spectrometer consists of two Fabry‐Perot interferometers arranged in tandem geometry, allowing the incoming spectra to pass through them six times. Simulations were performed in alignment and tandem modes. The alignment requirements of the system were meticulously outlined, and computations were conducted to validate the operational concept. Experimental results from the BLS spectrometer were also obtained and compared with simulation data. The comparison revealed a reasonable agreement between the OpticStudio simulations and experimental measurements, confirming the accuracy of the simulated model. This study underscores the effectiveness of using ZEMAX OpticStudio for optimization and highlights the potential of the BLS spectrometer for precise low‐frequency material wave detection in field applications.

Photonic integrated circuits (PICs) combine multiple optical elements on a single chip, enabling fast, compact, and scalable control of light. Determining their underlying physical parameters is essential for accurate modelling and device-level control, but this becomes increasingly challenging as architectures grow more complex. Inferring these parameters directly from spectral measurements offers a practical alternative to traditional calibration, avoiding the need for detailed device-specific models. In this work, we introduce a supervised machine-learning approach that learns onsite losses and resonant-frequency shifts in a coupled ring-resonator array from measured spectral power distributions. The networks recover these parameters with high accuracy across several experimental configurations and capture the key features that shape the spectral response. This data-driven method provides a scalable and non-invasive way to extract intrinsic parameters in programmable photonic circuits, supporting automated calibration and control.

The current generation of superconducting quantum computers rely on coaxial cables to transmit qubit control and readout signals. As the number of qubits in quantum computers approaches thousands, the passive heat load and limited bandwidth of the electrically conductive coaxial cables start restricting the scalability of quantum computers. Using optical fibres for signal routing could solve this scalability problem by providing high bandwidth, enabling signal multiplexing, and by reducing the heat load due to negligible thermal conductivity of optical fibres.

In my poster, I will discuss how optically driven Josephson Arbitrary Waveform Synthesizer (JAWS) can be used to convert optical pulses into electrical radio frequency signals in cryogenic conditions. I will present results showing that our JAWS, based on externally shunted Nb-AlOx-Nb junctions, can operate at pulse frequencies up to 60 GHz, which is four times faster than typical JAWS. Additionally, I will show characterisation data of a superconducting low-pass filter used in the output stage of the JAWS.

Optical feedback effects on the nonlinear dynamics of Vertical-Cavity Surface-Emitting Lasers (VCSELs) have been extensively investigated; however, the effects of feedback on the spatial coherence properties of VCSEL emission have received less attention. In this work, we carry out an experimental quantitative analysis of the coherece characteristics of a multimode VCSEL using the speckle technique. Measurements are independently performed for each linear polarization component of the emitted beam, as well as for the total output. We find that optical feedback does not significantly reduce speckle contrast compared to the solitary laser case, but on the contrary, it can cause a pronounced increase. This increase is interpreted in terms of a feedback-induced coupling mechanism that can phase-lock transverse modes that are, in the solitary laser, only partially locked. This effectively reduces mode competition and increases spatial coherence, thereby enhancing the speckle contrast.

Structured illumination is a versatile approach used in applications ranging from optical profilometry to advanced microscopy techniques such as Structured Illumination Microscopy, where it enables enhanced resolution and contrast. However, conventional implementations rely on bulky and alignment-sensitive optical components, limiting their integration into compact systems.

In this work, we present an integrated photonic circuit fabricated in glass by femtosecond laser micromachining for the generation of structured light patterns. This technique allows three-dimensional inscription of optical waveguides inside transparent substrates, enabling the realization of complex and compact photonic architectures. The proposed device integrates beam splitting, phase control, and spatial beam arrangement within a monolithic platform.

Multiple coherent beams are generated and arranged in a hexagonal configuration through a three-dimensional waveguide network. By exploiting interference among the beams, both one-dimensional and two-dimensional structured illumination patterns can be obtained. Dynamic control is achieved through integrated thermal phase shifters, which enable phase tuning without mechanical components. The resulting chip provides a stable, reconfigurable, and compact solution for structured illumination, demonstrating the potential of femtosecond laser micromachining for integrated photonic applications in microscopy and beyond.

Carbon nitride quantum dots (CNQDs) are promising fluorescent nanomaterials with photoluminescence properties strongly influenced by surface states and environmental conditions. In this work, CNQDs prepared from bulk graphitic carbon nitride (g-C₃N₄) were investigated using optical spectroscopy to elucidate their emission behaviour.

The materials exhibit a characteristic absorption band at ~270 nm and broad visible emission. Excitation-emission mapping reveals a dominant excitation region between 260-300 nm, with moderate excitation-dependent emission, indicating the presence of multiple overlapping emissive states.

Environmental sensitivity was evaluated by pH-dependent fluorescence measurements, which showed a pronounced increase in emission intensity under alkaline conditions. Additionally, Fe³⁺ ions induce concentration-dependent fluorescence quenching. However, measurements performed in aqueous media suggest that the observed response may involve both direct CNQD-metal interactions and concurrent pH changes.

These results highlight the complex photophysical behaviour of CNQDs and emphasise the importance of careful interpretation in fluorescence-based sensing applications

Upconverting nanoparticles (UCNPs) have great potential for ultrasensitive biosensing due to their background‑free detection enabled by the upconversion process, in which multiple low‑energy photons are absorbed and converted into higher‑energy emission. However, the main limitation of UCNPs is their low upconversion efficiency. One strategy to improve the upconversion luminescence is to use plasmon-enhanced techniques. There are two major challenges of plasmon-enhanced UCNPs: inhomogeneous plasmonic fields and plasmon coupling efficiency variations. Therefore, a systematic comparison between analog and digital readout is required to provide guidance for the design of robust and ultrasensitive biosensors based on plasmon-enhanced UCNPs.

We demonstrate label-free refractive index mapping of Sahiwal bovine sperm nuclei using dual-medium quantitative phase microscopy. By locating the maximum phase value, we decoupled the topography and precisely determined the refractive index of the nucleus.

This study focuses on the classification of optical fiber biosensor signals measured at seven different cancer cell concentrations. Data scarcity in biological signal acquisition was addressed by generating synthetic data using a conditional variational autoencoder (CVAE). Five classification algorithms were trained and evaluated to distinguish between the seven concentrations. The Random Forest model achieved the highest performance, with 77% accuracy on the original dataset, demonstrating the ability to capture concentration-dependent signal variations. However, a comparison of different proportions of real and synthetic data shows that increasing the proportion of synthetic data decreases accuracy. These results indicate that while generative models offer a potential solution to data scarcity, their effectiveness depends on their ability to accurately capture the underlying structure of biosensor signals.

A novel and custom deep learning models is proposed for prediction of microsatellite in colorectal cancer. In this proposed approach, the MobileNetV2 is developed to classify 9 different type of colorectal cancer tissue based on two public dataset NCT-CRC-HE-100K. The results have shown that the proposed technique is able to detect colorectal cancer tissues with an accuracy of 93%.

Due to their small dimensions and their unique optical properties, fiber-coupled

interferometric sensors are attractive candidates for industrial applications of

profilometry. Compared to microscope- and camera-based systems, they per-

form pointwise measurements of distance changes at high data rates and reach

a height resolution in the sub-nanometer range. However, the lateral resolution

is limited due to low numerical apertures of the focusing lenses. This work aims

at improving the lateral resolution considerably by using a photonic nanojet in

the measuring arm of the interferometer.

A rigorous model of a confocal microscope is used to simulate the measurement procedure, which is compared with real measurements. The aim is to reduce the gap between simulation and real measurement, by adjusting the simulation using reference measurements for the object generation. The simulation model combines a rigorous solver based on the Boundary Element Method (BEM) to simulate the light-surface-interaction with Fourier optics for the microscopic imaging. Two different surfaces are used as input for the model: the first is an ideal sinusoidal grating based on nominal parameters, while the second is a reference measurement of a single period of a diamond turned structure with sinusoidal cross section. The simulation results of both objects are compared with real acquisitions.

The use of drones as a platform for optical measurements induces several challenges. One of the key challenges in fringe projection profilometry is the degradation of image and projection quality caused by induced motion. To mitigate this problem, the effect of pulsed lighting and thus shorter exposure times is being investigated.

Scanning probe microscopy (SPM) is common method for nanometre and micrometre scale measurements. Traceability for the SPM measurements can be achieved either by calibration of the instrument or by direct interferometric measurement of the movements. In this paper two different ways for integration laser interferometers to SPM are presented. The instruments are custom built metrological SPM and a commercial SPM.

Metrological traceability to the SI unit system is needed in all measurements to ensure usability and commensurability of the result. Traceable scanning probe microscopes (SPMs) are typically custom-built instruments at national metrology institutes. In this paper two different instruments are presented. A custom-built 3-D metrological SPM and a commercial Jupiter XR SPM with interferometric measurement for XY movements.

Both instruments have different applications. Metrological SPM is mostly used for calibration of transfer standards, but also for the most accurate other measurements. The commercial instrument is used for e.g. topography, electrical measurements or measurements over a large wafer. The applications are e.g. large area positioning accuracy determination of components on photonic integrated circuits for quantum computing.

A snapshot Mueller matrix polarimetry using a spatial light modulator and a division-of-focal-plane polarization camera is proposed. The feature of this system is as a spatially encoded input states and simultaneous analysis allow single-exposure acquisition without moving optics. A partial Mueller matrix is reconstructed and validated with air and linear polarizers, enabling real-time imaging of dynamic samples.

Semiconductor manufacturing demands precise overlay metrology. Conventional diffraction-based overlay (DBO) exploits intensity imbalance between ±1st diffraction orders of biased gratings, providing a linear overlay response but relying on dedicated targets and offering limited flexibility for complex wavefronts. Dark-field digital holographic microscopy (df‑DHM) with angular multiplexing is a promising alternative, enabling coherent complex‑wave retrieval and computational corrections such as aberration correction and pupil apodization. While df‑DHM is typically single‑wavelength, multiwavelength operation can add depth sensitivity and best‑focus capability, essential for robust overlay control across diverse process stacks and consistent with multiwavelength DBO standards. To enable wavelength‑scanning, we use a supercontinuum source with an acousto‑optic tunable filter. However, low temporal coherence and angular beam separation result in a narrow coherence envelope, limiting the usable field of view. In addition, unequal glass components in the object and reference arms introduce wavelength‑dependent optical path length differences (OPD), causing coherence‑envelope shifts and strong signal variation in a wavelength sweep. We analytically model dispersive OPD contributions and apply least‑squares optimization to determine an optimal compensating glass thickness in the reference arm. This reduces residual OPD variation to below 10 µm, stabilizing the coherence envelope and phase. These results represent a first step toward dispersion‑controlled multiwavelength df‑DHM.

Subsurface damage in optical materials limits performance and lifetime of components used in high‑power laser systems. This work presents photothermal deflection as a sensitive and non‑destructive technique for detecting damage precursors beneath super‑polished surfaces. The method is applied to fused silica substrates polished by float‑bonnet polishing to assess the effect of slurry grain size on surface quality and the suitability of the polishing process for high-power laser applications

In high-power laser applications, surface contamination and defects often govern the optical material damage and degradation, limiting the maximum sustainable fluence. At short wavelengths, this reduction is more pronounced due to photon-induced processes. This study presents experimental methods to detect and analyse the causes and effects of component degradation. The methods include photothermal deflection spectroscopy, deep-UV Raman spectroscopy, laser-induced breakdown spectroscopy with detection in EUV, and mass spectrometry under EUV irradiation.

Dielectric metasurfaces enable compact wavefront control, but their fabrication often requires a slow electron-beam (e-beam), development, etching, and metrology sequence. We present an etch-free platform for buried dielectric metasurfaces based on single-shot e-beam exposure. This platform offers shorter write times, simpler data preparation, and improved mechanical robustness. Fabrication uses e-beam exposure of a thick PMMA resist on fused silica, where the local dose sets the hole diameter in a single shot. After development, conformal low-temperature atomic layer deposition of titanium dioxide fills the holes, forming buried high-index inclusions inside the resist. This approach offers a practical route for rapid prototyping in nanophotonics.

Integrated optical parametric amplifiers and oscillators are key building blocks for broadband optical communications, frequency conversion, and nonlinear light sources. However, their operational bandwidth is fundamentally limited by the need to fulfill phase-matching conditions. Recently, non-Hermitian optical parametric amplification has emerged as a new paradigm, where engineered optical loss—selectively applied to the idler mode—enables broadband parametric gain even in the absence of conventional phase-matching conditions. Here, we propose the realization of ultra-broadband and high-gain non-Hermitian optical parametric amplifiers on a silicon nitride-loaded lithium niobate on insulator integrated photonics platform. The work combines theory, numerical simulations, nanofabrication and experiments verifying the concept, based on designing microring resonators with wavelength-selective losses enabling idler suppression. The expected outcome is a high-gain (∼15–20 dB) on-chip optical parametric amplifier with an ultra-broadband bandwidth of several hundred nanometers. This bandwidth significantly exceeds conventional phase-matched devices, offering a compact and paradigmatic solution to, for example, significantly broaden the existing optical communication wavelength window near 1550 nm.

We investigate surface lattice resonances (SLRs) in plasmonic superlattices with a variety of configurations. By analyzing angle-resolved transmission spectra and the induced dipole moments, we show that selective illumination reveals strong radiative coupling between lattices, persisting over macroscopic distances. Furthermore, we demonstrate that checkerboard superlattices with alternating periods support multiple tightly spaced SLR modes, providing a promising platform for mode-locked multimode lasing.

Pulsed laser ablation in liquids (PLAL) is a nanoparticle (NP) synthesis technique that produces ligand-free, high-purity NPs without toxic by-products. Real-time monitoring of NP concentration during PLAL is crucial for controlling NP stability and functionality. Although UV-VIS spectrophotometers are viable instruments for this purpose, they are often expensive, massive, and difficult to incorporate into PLAL systems. Thus, in this work, we designed and constructed a compact, low-cost, and open-source device for in situ concentration measurement of PLAL-synthesized gold NPs, which serves as a model system for validating the proposed approach.

A Y2SiO5 bonded on glass hybrid photonic platform is here investigated, for enhancing the optical guided mode interaction with active rare-earth ions. The main challenging technological fabrication steps: bonding and waveguide dry-etching, are reported and discussed. Tailored optical waveguide design is proposed to accommodate technological fabrication constrains.

Here, we investigate the possibility for onset of non-perturbative effects in high Q-factor cavities. Our numerical results show resonance shifts and change in the bistability threshold as a function of cavity Q-factor caused by addition of higher-order Kerr terms into analysis. Clear shifts in the bistability curve and the bistability threshold are predicted, that depend on the inverse of cavity Q-factor. Our results highlight the potential need to include higher-order Kerr contributions into analysis of high-Q-factor resonators.

We present a preliminary study of polarization resolved light scattering from colloidal gold nanorods aimed at investigating the relationship between nanoparticle morphology and polarization preservation in ensemble scattering. Measurements are performed in a DLS-like geometry on a variety of gold nanoparticles. A polarization camera is used to capture scattered light enabling the measurement of Stokes parameters and the degree of linear polarization of scattered light. This optical response is compared with the longitudinal localized surface plasmon resonance peak, which is used as an indication of nanorod anisotropy.

This work investigates the emission behaviour of a vibration-induced emission (VIE)-active DMAC–phenazine derivative in dielectric and plasmonic environments. Thin films of the molecule deposited on quartz show mainly bent-state emission, while coupling to a broadband Ag/TiO₂/Ag plasmonic structure leads to dual fluorescence, indicating plasmon-assisted planarization of the molecular excited state. Time-resolved photoluminescence measurements further reveal faster excited-state decay on the plasmonic substrate, suggesting modified relaxation dynamics due to strong near-field interactions. The results demonstrate how plasmonic environments can influence molecular conformation and emission pathways in VIE-active systems. This study provides insight into plasmon-assisted control of molecular fluorescence and may be useful for designing tuneable photonic and optoelectronic devices based on conformationally responsive materials.

Plasmonic lightning-rod effect (PLRE) describes the formation of strongly enhanced and localized electromagnetic fields at the sharp features of plasmonic structures. Intuitively, this effect is considered a key principle for the meticulous design of plasmonic structures. Our original study involved only one plasmonic material (gold). Here, we extend our analysis to multiple plasmonic materials, in particular, silver and aluminum.

Silicon-Air exhibits strong Fresnel reflection due to its high refractive index contrast, leading to considerable optical loss in silicon-based photonic devices. To address this issue, we present a programmed plasma-enhanced atomic layer deposition (PEALD) approach for anti-reflective coating fabrication on silicon. By precisely controlling the deposition sequence and process parameters, thin films with tunable thickness and refractive index can be realized, allowing accurate destructive interference at the silicon surface. This method enables the design of anti-reflective coatings beyond conventional fixed-index materials and provides a versatile route for optimizing reflection suppression at target wavelengths.

We demonstrate a tailorable plasmonic lattice nanolaser supporting simultaneous lasing in topologically distinct modes without mutual phase correlation. By tuning the diameter of gold nanoparticles in an optically pumped lattice, we achieve single- and dual-mode lasing involving modes with different topological and polarization characteristics. Analysis on the source plane and in the far field show that the modes are mutually incoherent and exhibit no fixed phase relationship.

Silicon-on-insulator (SOI) is the ubiquitous platform for integrated photonic devices, yet silicon’s large thermo-optic coefficient makes device performance highly sensitive to temperature fluctuations. This limits the deployment in real-world environments where thermal stability cannot be guaranteed. Subwavelength grating (SWG) waveguides offer a promising, purely geometric route to mitigating thermo-optic sensitivity in SOI waveguides. In this work, we report a computational study of the temperature dependence of the effective refractive index of the fundamental transverse-electric (TE) Floquet-Bloch mode in SWG waveguides as a function of their geometrical parameters. Results are obtained via 3D finite-difference time-domain (FDTD) simulations for SWG waveguides and an eigenmode solver for strip waveguides. The fundamental TE Floquet-Bloch mode in SWG waveguides is significantly less sensitive to temperature than in strip waveguides of equivalent widths. We show that judicious selection of SWG geometric parameters can reduce temperature sensitivity up to fourfold compared to conventional strip waveguides, providing a design basis for athermal photonics devices currently under development.

Mode-locked fiber lasers are widely used in various applications. While conventional saturable absorbers (SAs), such as semiconductor saturable absorber mirrors, graphene, and carbon nanotubes, have been extensively studied, they still have inherent limitations in performance and fabrication. In this work, we propose an Indium tin oxide (ITO)-gold nanorod (GNR) metasurface SA that exploits the coupling between a metallic metasurface and an epsilon-near-zero (ENZ) material. Numerical simulations predict a primary resonance near 1060 nm and a secondary resonance near 1460 nm. The fabricated sample shows a primary resonance at 1045 nm and a secondary resonance at 1440 nm. Nonlinear transmission characteristics show a modulation depth of 6.4% and a saturation intensity of 13.3 MW/cm2. When incorporated into a Yb-doped fiber laser, noise-like pulse is achieved at a center wavelength of 1060 nm, with a pedestal pulse duration of 133 ps, and a spike pulse duration of 122 fs.

Cnoidal waves, as exact periodic solutions of the nonlinear Schrödinger equation (NLSE), constitute a diverse class of nonlinear wave states that bridge sinusoidal oscillations and soliton trains. Here, we experimentally demonstrate, for the first time, that a cnoidal wave background can independently host both bright and dark solitonic excitations as distinct nonlinear attractors within a passively mode-locked erbium-doped fiber laser governed by nonlinear polarization rotation. Operating within a 25 m ring cavity with a net anomalous group-velocity dispersion of −0.17 ps^2, stable cnoidal wave states with polarization-switchable temporal periods of 3.11, 4.44, and 24.88 ns are generated at 124 mW pump power, exhibiting an RF SNR of 43 dB. Systematically varying the pump power drives a sequential bifurcation through which bright and dark solitons emerge independently on the periodic cnoidal carrier,offering new opportunities for reconfigurable dark-pulse laser engineering and advanced nonlinear photonics.

Kerr frequency combs generated in high-quality-factor optical microresonators have attracted considerable attention due to their potential applications in precision metrology, high-speed telecommunications, and beyond. Understanding their coherence properties is essential for the development of energy-efficient, compact, and low-noise light sources. In particular, the interplay between pulsed injection, intrinsic noise, and optical feedback can enable the realisation of highly coherent and energy-efficient microcombs. We investigate the coherence properties of Kerr frequency combs within the framework of the Lugiato–Lefever equation. Specifically, we compute both numerical and analytical values of the phase noise and timing jitter arising from pump noise and thermal fluctuations. We begin by considering optical injection from a noisy continuous-wave (CW) source and demonstrate that optical feedback induces linewidth narrowing through a mechanism analogous to that observed in external cavity lasers. In the case of optical injection from a pulsed source, we calculate the locking range of the microcavity repetition rate and show that unlocking occurs via either an Andronov–Hopf or a saddle-node bifurcation. Finally, we develop a theoretical framework to analyse the stabilisation of the pulsed source through optical feedback.

High-entropy alloy nanostructures (HEA-NSs) are promising for catalysis and materials science but lack a universal atomic-level synthesis strategy. Here, we report a femtosecond laser method for preparing HEA-NSs spanning single atoms to ~100 nm nanoparticles on nearly any substrate. Starting from a homogeneous metal-ion solution, ultrafast electron dynamics drive rapid, nonselective reduction within ~100 ps, followed by nucleation and diffusion-controlled growth. Early-stage confinement suppresses phase segregation and enables atomic-level mixing of otherwise immiscible elements, offering a robust route to metastable multicomponent nanoparticles.

We investigate all-optical excitation of spin-wave modes in a 60 nm ferromagnetic Fe80Al20 thin film using time-resolved magneto-optical Kerr effect (TR-MOKE). Structural and compositional measurements confirm the film quality and the stabilization of the ferromagnetic A2 phase at room temperature. The transient Kerr signals show clear field-dependent oscillations, indicating laser-induced spin precession. Fast Fourier transform and dispersion analysis identify a low-frequency Kittel mode and an intermediate Damon--Eshbach mode. A higher-frequency resonance could not be consistently explained by conventional spin-wave models and is instead linked to magnetoelastic coupling. Time-domain thermoreflectance measurements reveal coherent acoustic phonon modes with overlapping frequencies, supporting this interpretation. The work demonstrates that Fe80Al20 supports rich ultrafast spin dynamics and hybrid spin-phonon interactions, making it a promising platform for magnonic and spintronic applications.

Optical skyrmions - light fields with nontrivial Stokes topology -offer intrinsic robustness and rich polarization structure, yet compact and versatile control remains elusive. Here, we introduce dual-functional dielectric metasurfaces for the on-demand generation and reconfigurable control of skyrmionic polarization textures during propagation. Leveraging anisotropic metaatoms, our platform enables simultaneous, asymmetric manipulation of orthogonal polarization states within a single element, producing full Poincaré beams with both 2D skyrmionic and 3D hopfionic topologies. Advanced phase engineering further enables a rich variety of dynamical effects in space, as polarization beating and topological reconfiguration. This work establishes a compact and scalable route to topological light control, unlocking new opportunities for robust photonic technologies based on topological invariants.

We present and experimentally demonstrate a new design recipe for spin-decoupled metaoptics capable of tailoring the propagation dynamics of polarization textures in Bessel-Gaussian vector beams. In contrast to conventional optical elements, these planar devices independently encode distinct phase profiles for the two orthogonal circular-polarization components (left- and right-handed), enabling precise control over the evolution of the resulting vector beam along the propagation axis. The technique allows the direct realization of dynamic effects such as polarization beating, topological charge evolution, and oscillatory local non-separability, opening new possibilities for spatiotemporal field engineering and offering a new versatile platform for structured-light applications in integrated photonics, with potential impact in optical manipulation and information technologies.

Orbital angular momentum (OAM) of light, stemming from a twisted phase front, is useful for many different applications such as resolution enhancement, multiplexing in optical communications, advanced sensing schemes, and high-dimensional quantum information processing, to name a few. Converting the fundamental Gaussian mode emitted by a single-mode fiber into a desired OAM mode usually requires an additional optical component. In this work, we demonstrate a scheme to nanostructure a single-mode fiber through direct laser writing of nanogratings leading to the controlled emission of higher-order OAM modes. The fiber is a standard telecom fiber, whose fundamental Gaussian mode is converted into a higher order OAM mode by spatially structuring the birefringence of the fiber core through the written nanogratings. Thereby, we enable an efficient, simple, and versatile scheme to the generation of twisted light.

We demonstrate a Mach--Zehnder interferometric scheme for a controlled spatial splitting of phase singularities, while conserving the total orbital angular momentum. The configuration uses, in one arm, a Gaussian or annular beam with a uniform phase and, in the other arm, a flat‑top beam with a spiral wavefront. We derive analytical conditions that determine the radial and azimuthal coordinates of the singularities in the output fields, and experimentally verify that these positions can be tuned by varying, respectively, the intensity and phase of the uniform‑phase input beam. We extend this scheme to partially coherent beams, where we find that the correlation between the interfering beams can affect the splitting and dynamics of split phase singularities.

We investigate the orbital angular momentum (OAM) and topologi-

cal charge of elliptic optical fields, where broken cylindrical symmetry compli-

cates the standard description of structured light. By employing an analytical

Hermite–Gaussian modal decomposition and the canonical OAM operator, we

track the dynamical evolution of OAM density and phase structures in ellip-

tically deformed Laguerre-Gaussian and Hermite-Gaussian beams. Our anal-

ysis yields three primary insights: We demonstrate that an elliptic Laguerre-

Gaussian beam may "hide" its topological charge upon propagation. We further

show that the intrinsic OAM density of such beams can be viewed as a dy-

namical quantity dependent on the global field structure. Finally, we predict

‘transient vortices’ in elliptic Hermite-Gaussian beams. These vortices are lo-

cal singularities that emerge during propagation without carrying total angular

momentum.

Spatial laser beam shaping is nowadays a widespread and fundamental tool in various

areas of physic. By means of a Spatial Light Modulator (SLM), one can alter the phase (or amplitude)

of a laser beam in order to control its spatial distribution in a given plane in space. However,

manufacturer-provided software is usually limited in the choice of target electric field distributions

as well as in the available phase retrieval algorithms. In this context, we propose an open-source

toolbox called PyMoDAQ BeamShaping, written in python, that enables users to orchestrate and

simulate a laser beam shaping experiment.

The interaction of tightly focused light with refractive-index stratified media can significantly modify optical trapping through enhanced spin–orbit interaction (SOI) of light. We present a combined theoretical, numerical, and experimental study demonstrating how refractive-index engineering enables controlled manipulation of optical force landscapes using a single Gaussian beam. By varying refractive-index mismatches and focusing conditions, we observe enhanced Spin-Hall shifts, tunable spin angular momentum density, and the formation of multiple stable trapping sites along the optical axis.

Using the Debye–Wolf diffraction formalism and Generalized Lorenz–Mie Theory, we model the focused field and optical forces in multilayer dielectric environments. Numerical simulations reveal that stronger refractive-index gradients induce spherical aberration and SOI effects, leading to axial elongation of the focal region and the emergence of multiple localized intensity maxima. These modified force landscapes support simultaneous trapping of particles at different axial planes, enabling three-dimensional optical manipulation without complex beam shaping.

The proposed approach offers a simple and scalable platform for multi-plane trapping, volumetric particle assembly, optical binding, force spectroscopy, and bio photonic applications, establishing refractive-index engineering as a powerful route for three-dimensional optical manipulation with minimal optical complexity.

In this paper, we introduce a new regime of resonant electromagnetic scattering, termed the “Roly-Poly” effect, in which a deeply subwavelength high-index dielectric particle preserves a fixed scattering direction in the laboratory frame independent on the incident wave direction or polarization. The effect arises from engineered bianisotropic coupling between electric dipole, magnetic dipole, and magnetic quadrupole modes in particles with C∞v symmetry. We develop a multipolar formalism linking incident plane waves to the particle eigenmodes and show that arbitrary excitations can access the same directional scattering state. As a numerical example, we analyze a high-permittivity hemispheroidal particle and identify a resonance at 4.68 GHz, where invariant directional scattering is observed for several distinct excitation configurations. Unlike conventional or generalized Kerker effects, where directionality is tied to the incident wave vector, the proposed mechanism enables excitation-independent, laboratory-frame-fixed scattering, opening new opportunities for robust nanoantennas, metasurfaces, sensing, radar, and cloaking applications.