Conference Agenda

The integration of large-area and transparent all-dielectric metasurfaces capable of sustaining photonic bound states in the continuum (BICs) with biomolecular recognition elements such as aptamers and molecularly imprinted polymers (MIPs) presents a promising avenue for achieving ultrahigh sensitivity in biosensing applications. BICs, distinguished by their infinitely high Q-factors and non-radiative nature, offer exceptional opportunities for enhancing light-matter interactions, thereby enabling unparalleled sensitivity to minute variations in refractive index. By leveraging the unique properties of BICs within photonic crystal slabs and coupling them with selective recognition elements, we aim to develop highly selective and sensitive biosensing platforms capable of detecting these analytes at trace levels, even at pico- and femtomolar concentrations. Here we present recent results regarding BIC-based biosensors in detecting and quantifying various biomolecules, including proteins and toxins in food. Furthermore, we present a novel sensor platform that enhances the BIC sensing principle with a MIP cladding layer tailored for specific binding to transforming growth factor-beta (TGF-β), a pivotal cytokine involved in diverse cellular processes. These advancements represent a significant stride in biosensing technology, offering versatile and efficient platforms with broad applications across scientific, industrial, and societal domains.

Achieving a robust chiral response in plasmonic metasurfaces is among key goals of current nanophotonic research. In this work, we theoretically show that the circular dichroism (CD) of a metal metasurface can be maximized by exploiting the concept of a bound state in a continuum (BIC) together with symmetry breaking. We consider a gold metasurface with a deformation of circular holes into oval holes. The chiral response at small values of the angle of incidence is dominated by a quasi-BIC, with nearly maximal values of the absorption CD that are almost independent of the deformation. Strong emission CD is also demonstrated. Symmetry analysis and mode profiles show that the extrinsically chiral response does indeed follow from a symmetry-broken BIC, and is associated with a strong enhancement of the local electrical field. The concept of a plasmonic BIC with symmetry breaking provides a robust pathway to increase the chiral response in metal metasurfaces and opens research opportunities in chiral plasmonics that combine narrow resonances with local field enhancement.

While the classical concept of phase of a coherent oscillation is a well defined notion, many attempts to describe its quantum mechanical counterpart failed. Here, we show a nouvel formulation of the quantum phase operator, which encompass previous problems and can be applied to any oscillatory system, as mechanical oscillator or electromagnetic field. Our formulation starts from a two-dimensional harmonic oscillator, and uses development by Newton’s binomial identity to action of the operator on any Foch state or linear combination of Foch states. We also introduce a physical interpretation of non-integer state number of the harmonic oscillator, overcoming a major limitation for the interpretation of the previous suggested forms of the phase operator. Applications of this novel approach to monomode displaced gaussian beam and doubled displaced states are also shown. Our formulation of the quantum phase operator bypasses the requirement of P, Q, or Wigner representation in the phase space and can be directly applied to Fock states. This approach offers a convenient mathematical framework for manipulating and analyzing phase properties in uantum systems.

We employ an ab initio Maxwellian approach using quasinormal-mode theory to derive an "exact" Maxwell evolution (EME) equation for resonator dynamics. The new differential equation bears resemblance to the classical one found in coupled-mode-theory (CMT); however, it introduces novel terms embodying distinct physics, suggesting that the CMT predictions could be faulted by dedicated experiments. The new equation is anticipated to be applicable to all electromagnetic resonator geometries, and the theoretical approach we have taken can be extended to other wave physics.

Stimulated Raman scattering in transparent glass-ceramics (TGCs) based on bulk nucleating phase Ba2NaNb5O15 were investigated with the aim to explore the influence of micro- and nanoscale structural transformations on Raman gain. TGCs are composed of nanocrystals that are 10–15 nm in size, uniformly distributed in the residual glass matrix. A significant Raman gain improvement for both BaNaNS glass and TGCs with respect to SiO2 glass is demonstrated, which can be clearly related to the nanostructuring process.

We study coherent perfect absorption in organic microcavity resonators and extend these principles

and our findings to more complex microresonator systems that, beyond absorption, also possess additional cavity energy dissipation mechanisms. The experimental approach uses laser interferometry to closely monitor the energy fluxes within the system at all device ports as a function of the device geometry and the phase relationships of the incident beams. A particular focus is on optical systems based on 2nd order Bragg gratings, which are crucial for the operation of organic distributed feedback (DFB) lasers or as light incouplers in optical waveguiding films. Coherent control allows the diffraction efficiency of the underlying grating to be tuned over a wide range of values. This strategy allows significant optimisation of resonator structures for high efficiency light coupling in optical waveguides and fine tuning of grating parameters for the most efficient optical mode conversion.

With the development of compact optical devices, there is an increasing demand for the integrated photonic platform. Here, we fabricated planar resonant cavities for surface waves on one-dimensional photonic crystals, based on reverse design. The cavity is coupled to a linear waveguide. Experimental data proved the injection of Bloch Surface Wave (BSW) into the waveguide with a narrow bandwidth. Our work offers a platform to facilitate integration of single photon sources on BSW-based chips.

Chirality is characterized by the absence of mirror symmetry , it’s an intrinsic property of certain entities in the universe and influences molecular interactions and properties. Measure circular dichroism (CD) using a circular polarized light is a standard technique but its sensitivity is often limited. In this work , we explore extrinsic chirality, a property arising from asymmetric achiral materials , using a photo-acoustic spectroscopy. Photo-acoustic spectroscopy allows direct measurement of local absorption, by monitoring the heat produced and transferred to the surrounding air, regardless the transmitted, reflected, and scattered light that flows away from the sample. In conventional techniques, the CD is usually measured by taking into account only the extinction as transmitted (or reflected) light. In this study, we introduce a new PAS setup that employs an oblique-incidence laser to study extrinsic chirality of metasurfaces made of polystyrene nanospheres asymmetrically coated with Ag. Our experimental results reveal intriguing CD trends dependent on the angle of incidence and wavelength, indicative of extrinsic chirality. This study expands the application of PAS, enabling simultaneous analysis of multiple wavelengths and providing valuable insights into chiral metasurfaces.

Laser direct writing (LDW) systems offer remarkable opportunities to sculpt materials at the micro and nanoscale. However, traditional LDW methods are limited in throughput because of their inherent serial nature– material modification occurs point-by-point. Here we propose a paradigm shift for LDW systems, from point-by-point to region-by-region operations. Our approach leverages ultrasonic waves to shape the laser radiation. Piezoelectric actuators, immersed in water, generate acoustic and, thus, density or refractive index waves, stationary in space and oscillating (MHz) in time. A laser beam traveling through such an acoustically controlled medium gets diffracted and forms interference patterns as well as multiple shape-tailored laser beamlets. Synchronization of the arrival of laser pulses with respect to the refractive index oscillation enables the selection of different inference patterns or beamlet configurations at the unsurpassed speed of MHz. Our system is simple and can be easily integrated into traditional LDW systems. This allowed us preparing micro and nanostructures over a large area (~cm2) of a sample in either additive or substrative mode. We validated our idea by preparing and stitching together, while scanning a sample surface with user-selectable laser patterns, pixels with different either nanostructured colorations or wettability.

MoO3 is extensively studied in the mid infrared range due to the strong anisotropy of its optical properties. We investigate the mid-infrared thermo-optical properties of polycrystalline alpha-phase Molybdenum trioxide (-MoO3) thin films grown onto SiO2 substrates in the temperature range 20°C-250°C reporting a thermo-optic coefficient of the mean order of 10-4 K-1.

Significant advances in mid-infrared optical technology depend on the development of innovative materials blending the properties of metals and insulators. In our work, we have systematically explored the thermochromic phase transition of vanadium dioxide. By introducing tungsten doping at room temperature through pulsed laser deposition technique onto sapphire substrates, we were able to precisely tailor the material's infrared optical responses. Our control over the tungsten concentration enabled us to finely tune both the amplitude and frequency of optical phonon resonances, as well as the free-electron response.

Molybdenum disulphide (MoS2) and is a transition metal-dichalcogenides (TMD) material has layered structure. Recently it has drawn significant attention for exploring optoelectronic and photonic properties at sub-nanometre scale. The TMDs possess direct bandgap which is quite attractive for device engineering and applications in photovoltaic, energy storage, and bandgap engineered light-sources. We have synthesized 2H MoS2 using hydrothermal synthesis at 240 ⁰C for 24 h. The as synthesized powder was used for the fabrication of MoS2 thin films using femto-second pulsed laser deposition (fs-PLD). The deposited films are stoichiometrically congruent with that of synthesized material. The materials were characterised using XRD, UV-vis absorption spectroscopy and Raman spectroscopy. Figure 1 below shows the Raman spectra of MoS2 films grown at different temperatures (400 ⁰C and 600 ⁰C). Shift in the Raman bands are seen for the films deposited at different temperatures. The structural and optical properties of deposited films were analysed and compared. Such a comparative analysis may offer materials fabrication platform in future for engineering optoelectronic and photonic devices on silica glass and silicon platforms.

Terahertz (THz) time-domain spectroscopic ellipsometry (TDSE) is a powerful, self-reference, and non-destructive technique for characterizing the electrical and optical properties of a wide range of materials including semiconductors such as doped silicon wafers. By analysing the polarization changes of THz pulses reflected off the silicon samples, TDSE provides detailed information on carrier concentration, mobility, complex conductivity, and complex dielectric response. This method leverages the unique sensitivity of THz radiation to free carrier dynamics in semiconductors, enabling precise measurements of doping levels, conductivity, and hence resistivity at once. The study demonstrates the capability of THz TDSE in distinguishing between different doping types (n-type and p-type) and concentration level, providing critical insights for semiconductor research and fast quality control in silicon wafer production.

Ultrafast laser micromachining is a technological innovation with exciting potential for many applications and has led to impressive advances in the study of light-matter interactions. In this context, the laser-assisted wet etching fabrication technique has opened new frontiers in the optofluidic lab-on-a-chip, i.e. complex and easy-to-use microsystems capable of integrating multiple physicochemical processes on a single platform to replicate specific chemical, biological and medical tests typically performed in a laboratory. These miniaturised multifunctional laboratories exploit the synergy between the high sensitivity of optics and the unique ability to manipulate small quantities of microfluidics to develop a new frontier of analytical devices. The chips can be manufactured in monolithic 3D versions with no geometric constraints and are fully embedded in the substrate (typically fused silica). In addition to the advantage of using an inert substrate (strategic for biological applications), the elimination of the sealing step and the high mechanical strength offer numerous advantages. To demonstrate the potential of this new sensing platform, we report on the benefits of integrating in-plane 3D micro-optics to increase the S/N in-chip spectroscopic analysis in two case studies: flow cytometer devices and innovative chips for real-time Raman analysis of bio-samples in flow, even non-transparent ones.

Optothermal manipulation of small objects ranging in size from micrometers down to nanometers has demonstrated a high degree of control over particle motion through a combination of optical and thermal forces. Here, we show that long-range optofluidic flows can be induced via the absorption of light on plasmonic nanostructures creating localized hot spots. Through temporal and spatial light modulation, we can precisely engineer fluid flows by controlling the thermal landscape. We combine in-situ measurements of induced thermal fields using optical diffraction tomography (ODT) with 3D optical tracking of particles via off-axis digital holographic microscopy (DHM) allowing us to precisely monitor light induced environmental changes. With the help of simulations, we analyze the individual contributions stemming from the thermal and optical forces. This comprehensive toolbox allows us to design specific fluid patterns in 3D creating optofluidic boundaries and obstacles that steer particle motion. Alternating between different patterns of illumination over time creates various types of microfluidic actuators such as pumps, traps, and valves, all within a single chip environment. Our optofluidic approach provides an alternative pathway to develop multifunctional microfluidic chips for integrated sorting, detection, and analysis.

Motivated by the need for improved platforms in biomedical research, this study addresses challenges associated with traditional Ussing chamber systems, widely used in studying biological barriers like the epithelial barrier of the gut. These challenges include complexity, high sample volumes, and limited compatibility. By combining stereolithography and soft lithography techniques, a microfluidic Ussing chamber is manufactured, overcoming these limitations, and incorporating compatibility with microscopy. Validation through Trans-Epithelial Electrical Resistance (TEER) measurements confirms its efficacy in assessing ion permeability dynamics, utilizing Caco-2 cell monolayers. The study showcases the capability of the manufactured chamber for sensing impact of calcium on tight junctions.

Agriculture challenges to reduce its environmental impact and to improve control over agricultural crops of agriculture are numerous. We develop here an optical integrated probe as potential answer to some detection challenges, based on a RIB chalcogenide waveguide. Early results have shown that the fabrication process induces sidewall roughness potentially altering the sensitivity of the probe. The numerical tool used here implements an approximation allowing to take into account sidewall roughness on propagation losses. This code is based on finite element method. Results show that sidewall roughness have a higher impact on losses for narrow waveguides.

Despite significant progress in the detection of small microplastics, the detection of such particles still faces problems caused by the limitations of current detection methods. We introduce optical methods for the analysis of individual microplastics and the fabrication of a substrate using plasmonic particles to detect plastic nanoparticles. We summarize recent experimental activities involving the construction of portable Raman tweezers that can be used for analysis of microsplastics. Optical trapping is complemented by nanoimprinting of plasmonics nanoparticles that enables create the "active" aggregates that can be used for Surface Enhanced Raman Spectroscopy (SERS) detection and as plasmon-enhanced thermoplasmonic concentrators for nanoscale plastics. The principle of nanoimprinting is based on the dominance of the scattering force (compared to the gradient force) for plasmonic particles, this force pushes particles in the direction of propagation of the light beam. In both cases, enhanced sensitivity is demonstrated, allowing the detection of nanoplastics of size orders of magnitude lower than what can be achieved by Raman spectroscopy. This study demonstrates that the combination of two optical manipulation techniques are capable of filling the technological gap in the detection of plastic particles ranging in size from a few tens of nm to 20 µm.

Hepatocellular carcinoma (HCC), the most common form of primary liver cancer, represents a global health challenge due to its complexity and the limitations of current diagnostic techniques. By combining Raman spectroscopy and Artificial Intelligence (AI), we have succeeded in classifying tumor cells. In fact, we have performed a first Raman spectral analysis based on the characterization and differentiation between uncultured primary human liver cells derived from resected HCC tumor tissue and the adjacent non-tumor counterpart. Biochemical analysis of the collected Raman spectra revealed that there is more DNA in the nuclei of the tumor cells than in non-tumor cells. We then develop three machine learning approaches, including multivariate models and neural networks, to rapidly automate the recognition and classification of the Raman spectra of both cells. To evaluate the performance of the developed AI models, we prepared and analyzed two additional cell samples with a ratio of 4:1 and 3:1 between tumor and non-tumor cells and compared the obtained results with the nominal percentages (accuracy of 80 and 60%, respectively). These results confirm that the models are able to make classifications at the level of a single spectrum, indicating the possibility of rapidly analysing and classifying a primary HCC cell.

Metastasis stands as the leading cause of mortality among colorectal cancer (CRC) patients. Galunisertib (LY2157299, LY) is a small molecule demonstrating promising anti-cancer effects by targeting the Transforming Growth Factor-beta (TGF-β) pathway. This route plays a pivotal role in initiating the epithelial-to-mesenchymal transition (EMT), a critical process for metastatic spread. Unfortunately, LY chronic treatment causes undesired effects. To mitigate these side effects, nanoscale drug delivery systems have emerged as a transformative approach in cancer treatment, enhancing drug effectiveness while minimizing toxicity. In this study, we introduce a hybrid nanosystem (DNP-AuNPs-LY@Gel) comprising porous diatomite nanoparticles decorated with plasmonic gold nanoparticles (AuNPs), encapsulating LY within a gelatin shell. This multifunctional nanosystem demonstrates efficient LY delivery, EMT reversal in CRC 2D and 3D cultures, and anti-cancer effects in vivo. Moreover, the nanosystem allowed the quantification with sub-femtogram resolution of the drug intracellularly released using surface-enhanced Raman spectroscopy (SERS). The release of LY is triggered by CRC cell acidic microenvironment. Real-time monitoring of drug release at the single-cell level is achieved by analyzing SERS signals of LY within CRC cells. The heightened efficacy of LY delivery through the DNP-AuNPs-LY@Gel complex offers a promising alternative strategy for reducing drug dosages and subsequent undesired effects.

The presence of microplastics in various food products has raised significant concerns regarding potential health risks for consumers. Among these products, milk, being a staple in many diets, has attracted attention for its widespread consumption and nutritional significance. In this work, a metrological method was developed to accurately quantify and characterize small microplastics (100-5 μm) in milk powder (infant formula) using micro-Raman (μRaman) technology, combining enzymatic digestion, organic matter removal under alkaline conditions, chemical analysis, microwave digestion and a final filtration step through a silicon (Si) filter. The present methodology was developed and validated for several polymers using both commercially available reference materials with defined dimensions and morphology, and more representative polydisperse materials.

Regarding PET microplastics, size, number and numerical distribution were previously evaluated in an intervalidation study involving two different laboratories with different micro-Raman instrumentation to provide a reference number for this material. The analytical procedure was further validated in terms of microplastic recovery rate and quantification sensitivity with the calculation of LOD (limit of detection) and LOQ (limit of quantification)

Additives are excessively used in agriculture for the purposes of crop protection, and enhancement of the yield quality and quantity of the products. Although the use of these chemicals is necessary for the food industry, they are associated with short- and long-term effects on human health. Thus, their use should be regulated, and their detection is critical not only for human health but also for the environment and wildlife. In this study, the detection of additives by surface-enhanced Raman scattering (SERS) substrates is proposed. For this purpose, flexible substrates are prepared from poly(ethylene glycol) diacrylate (PEGDA) and gold Nanoparticles (AuNPs). The detection performance of the designed substrates was tested against sulfur dioxide (SO2). It was found that designed substrates can provide homogenous signal distribution and significant signal enhancement. Moreover, they can allow detection of SO2 in wine down to 0.4 ppm which is lower than the regulatory limits.

High-precision biosensors for single or few molecules detection play a central role in numerous key fields, such as environmental monitoring and healthcare for early-stage disease diagnosis. In the last decade, laser biosensors have been investigated as proofs of concept, and several technologies have been proposed. Here we propose a demonstration of polymeric whispering gallery microlasers as biosensors for detecting proteins at low concentrations. Free space microlasers have the great advantage of working without any need for waveguiding for input excitation or output signal detection. The photonic microsensors can be easily patterned on microscope slides and operate in air and solution. We could detect down to 400 pg of protein without specific binding, and few tens of pg/mL with specific binding.

New photonic techniques need to be developed to improve personalised medicine methods in tissue engineering. In the case of severe bone injuries, difficulties arise when creating platforms where cells required to be efficiently adhered. Femtosecond laser ablation appears as a versatile technique for modifying the surface of materials with high precision and neat outcomes. Thus, a strategy combining 3D printing of biopolymeric scaffolds and femtosecond laser ablation is proposed to design a device with enhanced material properties in terms of cell growth for bone tissue regeneration. Three different patterns were proposed, and it was proven that cell adhesion improvements rely on the pattern profile, assessing that grooved scaffold successfully increased cell adhesion and proliferation in comparison with micropitted samples.

Assessing HER2 expression in breast cancer cells holds significant diagnostic and prognostic importance. Traditional methods like immunohistochemistry and in situ hybridization suffer from low sensitivity and misclassification rates. In this frame, techniques such as vibrational microscopies can ensure, together with low costs and analytical speed, both high accuracy and precision. Herein, we propose a combined Raman and SERS approach for characterizing 4 breast cancer cell lines and normal cells with varying HER2 expression levels. We show that Raman spectroscopy offers a promising alternative, providing unique molecular fingerprints for cell types based on their biochemical signatures. Its non-invasive nature and ability to detect subtle changes in cellular metabolism make it ideal for cancer cell analysis. Coupled with machine learning techniques like PCA and LDA, Raman spectroscopy can classify different breast cancer subcategories accurately. Surface Enhanced Raman Scattering (SERS) further enhances sensitivity, allowing the detection of single molecules like HER2 receptors. Overall, our results enable fast screening of cancer subpopulation in terms of HER2 concentration and macromolecule cell content. Integration of Raman spectroscopy with SERS offers precise identification and opens avenues for personalized therapies

With continuously improving resolution of today’s (super-resolution) microscopes, a major technical limitation of light microscopy based image analysis is linkage error – a visualization error that is measured by the distance between the cellular target to be detected and the fluorescence emitter used for detection. The linkage error of standard labelled antibodies is caused by the size of the antibody and the random distribution of fluorescent emitters on the antibody surface. In this study, we describe a class of staining reagents that effectively reduce the linkage error by more than five-fold when compared to conventional staining techniques. These reagents, called Fluo-N-Fabs, consist of an antigen binding fragment that is selectively conjugated at the N-terminal amino group with fluorescent organic molecules, thereby reducing the distance between the fluorescent emitter and the protein target of the analysis. Fluo-N-Fabs also exhibit the capability to penetrate tissues and highly crowded cell compartments, thus allowing for the efficient detection of cellular epitopes in a wide range of fixed samples. We believe this class of reagents realize an unmet need in cell biological super resolution imaging studies where the precise localization of the target of interest is crucial for the understanding of complex biological phenomena.

The manufacturing rate of laser-chemical machining (LCM) is limited to avoid disruptive boiling bubbles in the process fluid. Adjustments to e.g. the laser beam or the fluid properties can increase the removal rate. However, the existing understanding of the surface removal mechanisms is insufficient to ensure the removal quality under these conditions. Thus, near-process measurements of the surface geometry and the surface temperature are required for an improved process modeling. Due to the complex process environment, no suitable in-process measurement technique for the geometry or surface temperature exists so far. This contribution presents an indirect geometry measurement approach based on scanning confocal fluorescence microscopy that is integrated into the LCM plant. As a result, it is shown that the approx. 200 μm deep micro-geometry of laser-chemically processed surfaces can be indirectly measured in-situ, i.e. inside the LCM system. The realized setup is designed in such a way that in future it will be additionally possible to measure the temperature by means of the fluorescence life-time.

Optical sensors based on a plasmonic multilayer stack, such as metal-insulator-metal (MIM), have attracted considerable attention over the past decades owing to their high resolution and high performance compared to conventional surface plasmon resonance (CSPR) sensors for bulk sensing (BS) applications. In this paper we show that CSPR is better than MIM sensors for thin film sensing, i.e. when a dielectric sensing layer (SL) is deposited on the outermost metal layer of the structure. We demonstrate that the deposition of a thin film SL on the top of the outermost-layer of an optimized multilayer structure, i.e. MIM, strongly decreases the evanescent electric field and the field enhancement at metal-SL interface and decreases the sensor’s sensitivity for MIM versus CSPR. By considering the theoretical and experimental results we demontrated that CSPR is more suitable than MIM for thin films sensing applications.

Nucleic acids are essential biomolecules for the functioning of cells. In past years, nucleic acids have been assessing their role in prognostics and diagnostics. The progress of nanotechnology has allowed the fabrication of various type of nanostructured biosensors able to detect them with high sensitivity and specificity. Among the available sensing mechanisms, the sensor technology based on Surface-enhanced Raman Spectroscopy (SERS) is frequently preferred for identifying nucleic acids. In these sensors, natural or synthetic oligonucleotide sequences, acting as probes to hybridize the target molecules, are immobilized on a plasmonic sensing platform. In particular, aptamers, short DNA/RNA sequences, are emerging as new recognition elements for their chemical stability and specificity. Here, we focus on the combination of a specific type of aptamer, a molecular aptamer beacon, and nanostructured SERS biosensors for a sensitive detection of nucleic acids.

We report the experimental and theoretical terahertz absorption characteristics of unprocessed crude oils from Kuwait oil wells. Using frequency domain THz spectroscopy technique between the frequencies from 2 – 18 THz (66 – 600 cm-1) and semi-empirical computational chemistry calculation, five (SA121T, SA-151TS, SA108T, SA-120T, SA159T) of the 30 crude oils revealed characteristic absorption peaks. Experimental data showed absorption peaks at 6.0 THz, 7.7 THz, 13 THz, and 16 THz. On the other hand, the calculated spectral bands of 10 nonane molecules were found at around 2.8 THz, 7.7 THz, 10 THz, and 16 THz. Although only two bands were predicted by the calculation, adding alkane molecules of different lengths (pentane to decane) resulted in the formation of new peaks. These preliminary results suggest that there is a mixture of different alkanes present in the investigated samples, a typical characteristic of unprocessed crude oil.

The localized surface plasmon resonance (LSPR) is a phenomenon which consists in a collective oscillation of free electrons in metal nanoparticles (NPs), it is very sensitive to any changing of the optical properties of the surrounding medium, for instance, provoked by the adsorption or desorption of molecules over metal surface. In our work we investigated the LSPR response of silver NPs chemically grafted onto transparent substrates and exposed to increasing quantities of water vapor inside a vacuum chamber. Extinction spectra are obtained by using an “in situ” UV-Vis spectrophotometer as a function of the vapor pressure inside the chamber. We studied the adsorption and desorption mechanism of vapor over plasmonic substrates. The huge sensitivity and the accessible and cost-effective equipment make these effects promising candidates for various sensing applications, including the environmental monitoring

A scattering snapshot hold an enormous potential for cell class and state classification, allowing to avoid costly fluorescence labelling. Beside convolutional neural networks show outstanding image classification performance compared to other state-of-the-art methods, regarding accuracy and speed. Therefore, we combined the two techniques (Light Scattering and Deep Learning) to identify living cells with high precision. Neural Networks show high prediction performance for known classes but struggles when unknown classes need to be identified. In such a scenario no prior knowledge of the unknown cell class can be used for the model training, which inevitably results in a misclassification. To overcome the hurdle, of identifying unknown cell classes, we must first define an in-distribution of known snapshots to afterwards detect out of distribution snapshots as unknowns. Ones, such a new cell class is identified, we can retrain our cell classifier with the obtained knowledge, so we dynamically update the cell class database. We applied this measurement approach to scattering pattern snapshots of different classes of living cells. Our outcome shows a precise cell classification, which can be applied to a wide range of single cell classification approaches.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

higher than 0.999.

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

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

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