bluuebunny/crossref_metadata_2025 huggingface dataset:
Boride-induced phase tuning of defect-introduced MoS2 nanosheets to boost the electrocatalytic hydrogen evolution reaction
Authors: Lee Dong Wook , Jin Xiaoyan , Yun So Yeon , Hwang Seong-Ju
Published: October 2023

Boride substitution for defect-introduced MoS2 nanosheets provides an effective way to tune the crystal structure of MoS2 and improve the HER electrocatalytic activity.
Self-powered triboelectric wearable biosensor using Scotch tape
Authors: Jang Moon-Hyung , Lei Yu , Conners Ryan T. , Wang Gang
Published: October 2023

The Scotch tape is the sensing element by exploring the interaction between tape polypropylene backing material and acrylic adhesive layer when pressing and releasing.
Genetically engineered bacteria: a new frontier in targeted drug delivery
Authors: Fooladi Saba , Rabiee Navid , Iravani Siavash
Published: October 2023

Genetically engineered bacteria have emerged as an exciting frontier in targeted drug delivery.
Predicting power plant emissions using public data and machine learning
Authors: Gu Jiajun , Sward Jeffrey A. , Zhang K. Max
Published: October 2023

We show that combining a variety of public datasets and non-linear machine learning models can predict emissions from electric generating units at good accuracy without any proprietary information.
Thematic Analysis of Personal Narratives Spoken by Autistic Adults of Underrepresented Genders
Authors: Coburn Kelly L. , Williams Diane L.
Published: October 2023

Purpose:

Underrepresentation of transgender men and women, gender-expansive people, and cisgender women in autism research has created barriers to appropriate, timely identification and supports that can improve quality of life. To address this need, this study investigated themes in spoken narratives produced by autistic adults whose genders are marginalized and compared them to those of cisgender men. These themes can provide insight into common topics among autistic narrators of diverse genders and dispel stereotypes based on previous research with cisgender men and boys.

Method:

Twenty autistic adults of diverse genders told stories about their personal experiences. Two stories from each participant were analyzed: (a)
Interest,
about something the participant really likes to do, and (b)
People,
about an experience they shared with others. Major themes and subthemes in the narratives were identified using reflexive thematic analysis.

Results:

Participants of all genders described how their personal interests connect them to other people, even when not explicitly instructed to do so. Major themes in the
People
narratives included specific places and opportunities to help. Participants shared
Interest
stories about multiple facets of the arts. Subthemes of nature and history were common in both narrative tasks.

Conclusions:

Autistic participants, especially women, trans men, and gender-expansive people, consistently emphasized the importance of connecting with other people in their personal narratives. This finding challenges antisocial stereotypes of autistic people. Improved representation of trans and gender-expansive people and cisgender women in research can contribute to better services and supports for autistic people.
Sulfur isotope ratios in the Large Magellanic Cloud
Authors: Gong Y. , Henkel C. , Menten K. M. , Chen C.-H. R. , Zhang Z. Y. , Yan Y. T. , Weiss A. , Langer N. , Wang J. Z. , Mao R. Q. , Tang X. D. , Yang W. , Ao Y. P. , Wang M.
Published: October 2023

Context. Sulfur isotope ratios have emerged as a promising tool for tracing stellar nucleosynthesis, quantifying stellar populations, and investigating the chemical evolution of galaxies. While they are extensively studied in the context of the Milky Way, they still remain largely unexplored in extragalactic environments.

Aims. We focus on investigating the sulfur isotope ratios in the Large Magellanic Cloud (LMC) to gain insights into sulfur enrichment in this nearby system and to establish benchmarks for such ratios in metal-poor galaxies.

Methods. We conducted pointed observations of CS and its isotopologues toward N113, one of the most prominent star-formation regions in the LMC, utilizing the Atacama Pathfinder EXperiment 12 m telescope.

Results. We present the first robust detection of C33S in the LMC by successfully identifying two C33S transitions on a large scale of ∼5 pc. Our measurements result in an accurate determination of the 34S/33S isotope ratio, which is 2.0 ± 0.2. Our comparative analysis indicates that the 32S/33S and 34S/33S isotope ratios are about a factor of two lower in the LMC than in the Milky Way.

Conclusions. Our findings suggest that the low 34S/33S isotope ratio in the LMC can be attributed to a combination of the age effect, low metallicity, and star formation history.
Near-infrared photodetectors based on embedded graphene
Authors: Crisci Teresa , Maccagnani Piera , Moretti Luigi , Summonte Caterina , Gioffrè Mariano , Rizzoli Rita , Medugno Mario , Iodice Mario , Coppola Giuseppe , Casalino Maurizio
Published: October 2023

In last years, the introduction of 2-dimensional materials such as graphene has revolutionized the world of silicon photonics. In this work, we demonstrate a new approach for integrating graphene into silicon-based photodetectors. We leverage a thin film of hydrogenated amorphous silicon to embed the graphene within two different photonic structures, an optical Fabry-Pérot microcavity, and a waveguide, achieving a stronger light-matter interaction. The investigated devices have shown promising performance resulting in responsivities as high as 27 mA/W and 0.15 A/W around 1550 nm, respectively.
Trajectory tracing dynamics in anisotropic microcavities
Authors: Hentschel Martina , Seemann Lukas
Published: October 2023

Ray-wave correspondence has proven a powerful tool in mesoscopic optics, in particular in the description of deformed microdisc cavities with a versatile application potential ranging from microlasers to sensors. New material classes such as graphene-based systems have enriched the field by adding Dirac Fermion optics as well as anisotropic material properties as further system parameters. The trigonally warped dispersion relation in bilayer-graphene billiards generalizes the concept of birefringence and opens unconventional ways of trajectory control in the interplay of dispersion relation and the cavity geometry as we illustrate in this contribution.
Beam steering experiments through an optical phased array with wavelength tuning
Authors: Muntaha Sidra Tul , Hokkanen Ari , Harjanne Mikko , Cherchi Matteo , Roussey Matthieu , Aalto Timo
Published: October 2023

In this paper, we have demonstrated the beam steering experiments with the help of our optical phased array devices. The lateral beam steering has been showed successfully with the wavelength through the tunable laser source. The number of output channels were 512 and the array width was kept more than a millimeter with a 2-µm pitch. The beam steering angle has been measured as 45° and the beam movement was 1°/nm. As the chip does not collimate the beam vertically, so, a commercial collimating lens has been used in the vertical direction.
Complex illumination system for fast interferometric measurements
Authors: Schober Christian , Lausmann Lisa , Treptow Kevin , Pruss Christof , Reichelt Stephan
Published: October 2023

Freeform metrology is an enabling technology for today’s research and advanced manufacturing. The Tilted Wave Interferometer is a full field measurement system for fast and flexible measurements. It is based on an off-axis illumination scheme based on a microlens array. In this contribution, we present a novel illumination system for the tilted wave interferometer, that allows to reduce the measurement time by a factor of four using parallelization based on wavelength multiplexing. Here we present a design solution that utilizes the flexibility of 3D-printing. The microlenses are realized as multi-order diffractive optical elements, providing a high efficiency compared to colorfilter based realizations. To boost the light efficiency of the novel illumination system further, a field lens functionality is added to the system by adding individual micro-prisms to each microlens. The system is manufactured by the use of grayscale two-photon polymerisation.
Modulating phase for adaptive optics and PSF shaping in bio-imaging: Requirements & development of a new deformable mirror tailored to microscopy
Authors: Harms Fabrice , Veilly Cynthia , Jasaitis Audrius , Dovillaire Guillaume , Levecq Xavier
Published: October 2023

Modern bio-imaging techniques such as light-sheet, multiphoton and PALM/STORM are now aiming to image more complex biological samples at larger depth and therefore face larger-amplitude and more complex aberrations. We provide an analysis of key requirements driving optimal implementation of adaptive optics (AO) in microscopy, with a focus on wavefront modulators. We show that some specifications of wavefront modulators such as linearity, hysteresis or actuators performance & layout can end up to better AO performance in microscopy systems, when specifically optimized for such use. We then provide design details and characterization results of a newly developed deformable mirror, and report on experimental images obtained from AO-enhanced microscopes based on the device, for several modalities such as light-sheet, multiphoton or super-resolution single molecule localization systems. Finally, we provide recommendations on how to define the right set of AO components, algorithms and overall method depending on modality, instrument and sample constraints.
Optical Design of a High Flux Setup in the Extreme Ultraviolet
Authors: Hofmann Oskar , Al-Juboori Haider , Danylyuk Serhiy , Juskin L.
Published: October 2023

Extreme ultraviolet (XUV) light applications are still a very promising field that was heavily enlivened by the definition of the new wavelength for semiconductor lithography within the XUV range. But the detection of XUV light is also important for the exploration in the field of space science (i.e., monitoring the formation and evolution of solar storms) and high-energy physics (i.e., dark matter detection). The advancement of this technology mainly depends on the performance optimization of XUV sources, optical systems and related photodetectors. In this work, the optical design of a high flux XUV setup was simulated and defined to optimise the beam path which is the backbone of the initial evaluation process for the characterisation of luminescent materials under XUV irradiation. Additionally, the paper focused on the conceptualisation and realisation of the experimental setup as well as the alignment of the optical components and the detector calibration.
Hyperspectral imaging of stone biofilms at the macroscopic scale
Authors: Candeo Alessia , Di Benedetto Alessia , Berti Letizia , Cappitelli Francesca , Villa Federica , Goidanich Sara , Valentini Gianluca , Manzoni Cristian , Toniolo Lucia , Comelli Daniela
Published: October 2023

The ability to observe traces of biological material on buildings and stone artworks is of particular importance in understanding how to best deal with them and maybe, in the future, even make use of biofilms for conservation science. We have identified hyperspectral imaging as a viable method for the efficient analysis of such biological materials. Thanks to the high throughput of our approach based on an interferometric method based on Fourier Transform, we were not only able to detect traces of biofilms on stone samples, but also to map in which areas these were found to have higher biological activity.
Femtosecond laser rapid prototyping and characterization of microfluidic device for particles sorting
Authors: Volpe Annalisa , Petruzzellis Isabella , Mezzapesa Francesco P. , Gaudiuso Caterina , Osellame Roberto , Ancona Antonio , Martínez Vázquez Rebeca
Published: October 2023

Rapid prototyping methods for the fabrication of polymeric labs-on-a-chip (LoC) are on the rise, as they allow high degrees of precision and flexibility. In this contest, the flexibility of ultrafast laser technology enables the rapid prototyping and high-precision micromachining of 3D LoC devices with complex microfluidic channel networks. In this paper, we describe the realization process of a microfluidic tool for fully inertial particles sorting. The microfluidic network was realized in polymethyl methacrylate (PMMA), exploiting femtosecond laser technology. The multilayer device was assembled through a facile and low-cost solvent-assisted method. In particular, we studied the particle focusing in curved inertial microfluidic channel with trapezoidal cross section. A particles focusing along the walls of the device, sensitive to particle size and flow rate, was observed based on the principle of Dean-coupled inertial migration in spiral microchannel.
Volumetric one-photon UVA hyperspectral light sheet imaging in mouse pre-implantation embryos - INVITED
Authors: Morizet Josephine , Chow Darren , Wijesinghe Philip , Schartner Erik , Dwapanyin George , Dunning Kylie , Dholakia Kishan
Published: October 2023

UVA one-photon hyperspectral light sheet imaging was performed here to capture and reconstruct three dimensional metabolic maps of mouse embryos during development. We explored numerically and experimentally the advantages of phasor-based hyperspectral approach for detecting embryo metabolism with a single wavelength excitation compared to the conventional detection approach using bandpass filters.
Imaging of calcium gradient oscillations in plant root hairs by light sheet fluorescence microscopy
Authors: Tortora Giorgia , Buratti Stefano , Grenzi Matteo , Costa Alex , Bassi Andrea , Candeo Alessia
Published: October 2023

Root hairs are a delicate single-cell system whose growth is regulated by a fine mechanism characterised by the presence of a tip-high Ca2+ gradient that shows regular oscillations in growing root hairs. We show a method based on the use of Light sheet fluorescence microscopy (LSFM) which allows the quasi-physiological analysis of Arabidopsis thaliana plant roots hairs with excellent spatial and temporal resolution over a wide field of view. We show how the healthy growing root hairs are linked to precise oscillations and how a disruption of this mechanism can be associated to specific genes.
Diffuser-based fiber endoscopy for single-shot 3D fluorescence imaging
Authors: Glosemeyer Tom , Lich Julian , Kuschmierz Robert , Czarske Jürgen
Published: October 2023

Minimally invasive endoscopy using coherent fiber bundles shows great potential for numerous applications in biomedical imaging. With a diffuser on the distal side of the fiber bundle and computational image recovery, single-shot 3D imaging is possible by encoding the image volume into 2D speckle patterns. In comparison to equivalent lens systems, a higher space-bandwidth product can be achieved. However, decoding the image with iterative algorithms is time-consuming. Thus, we propose utilizing a neural network for fast 2D and 3D image reconstruction at video rate. In this work, single-shot 3D fluorescence imaging with an ultra-thin endoscope is demonstrated, enabling applications like calcium imaging for in vivo brain diagnostics at cellular resolution.
Direct observation of infrared electroluminescence of high mobility graphene field-effect transistors
Authors: Rossetti Sylvio , Schmitt Aurélien , Abou-Hamdan Loubnan , Bretel Rémi , Bouchon Patrick , Baudin Emmanuel , De Wilde Yannick
Published: October 2023

In this presentation we will discuss our efforts based on high sensitivity infrared microscopy and spectroscopy to unravel the origin of super-incandescent emission of high-mobility graphene transistors.
Second harmonic generation from nano cavities milled in thin aluminum film
Authors: Zar Tchiya , Shavit Omer , Krause Alon , Salomon Adi
Published: October 2023

Second harmonic generation (SHG) is forbidden for centrosymmetric materials such metals. Yet, symmetry can be broken by introducing plasmonic nano-structures which lead to enhancement of the electromagnetic field at both the fundamental and the SH frequencies. Using non-linear microscopy, we experimentally demonstrate enhanced SHG from isosceles triangular cavities (~215 nm side length, 200 nm base) milled in thin aluminum film. Upon strong interaction between the cavities, they behave as a single unit and response in a coherent manner, i.e. SHG is observed from the coupled system. The hybridization between the cavities is not only dependent on the distance between them, but their spatial arrangement is found to be a crucial parameter. That is, the SHG efficiency can be enhanced upon different arrangement of the same cavities, holding the same distance between them. We characterize those cavities also by cathodoluminescence and show that the structure support plasmonic modes both at the fundamental and the SH frequencies.
Spin-to-orbital angular momentum transfer by second harmonic generation in thin dielectric films
Authors: de Ceglia Domenico , Coudrat Laure , Vincenti Maria Antonietta , Scalora Michael , Tanos Rana , Claudon Julien , Gérard Jean-Michel , Degiron Aloyse , Leo Giuseppe , De Angelis Costantino
Published: October 2023

We demonstrate spin-to-orbital angular momentum transfer in the bulk of nonlinear optical materials with a crystal symmetry that couples the longitudinal component of the pump field. Our predictions are exper-imentally confirmed with a thin film of gallium arsenide, which generates vortex beams of second-harmonic light when pumped with a CP Gaussian beam.
Transmission Gratings relying on Huygens Metasurfaces for short-wave to long-wave infrared applications
Authors: Flügel-Paul Thomas , Käsebier Thomas
Published: October 2023

In many spectroscopic applications, diffraction gratings are the pivotal optical component which is used to decompose white light into its spectrum. However, design and manufacturing of diffraction gratings for the infrared spectral domain operating in transmission bares its own challenges, i.e. a very limited choice of transparent materials. Here we present our effort on exploiting Huygens-metasurface structures for design and manufacturing of diffraction gratings intended for operation in the short-wave (around 2µm) up to the long-wave infrared region (>10µm). Silicon nano-pillars are the material system of choice since they exhibit the best compromise between optical performance and manufacturing feasibility. We present specific designs as well as measurement results of a demonstrator sample.
Robust method of metrology for direct phase measurement for nano-antennas
Authors: Le Gall Cécile , Bellanger Cindy , Primot Jérôme , Jaeck Julien
Published: October 2023

Optical metasurfaces allow the development of original and more and more complex optical functions. They are therefore facing a design and characterization problem. Indeed, they are more and more composed of complex patterns, with different types of antennas and non-periodic. This is why it is important to build libraries of nano-structures that can be used as building blocks to compose optical functions. Therefore, we propose a direct phase measurement metrology method for optical nanostructures. Using lateral shift interferometry, our technique allows to simultaneously characterize in amplitude and phase nano-antennas of all types, shapes and materials, and thus to experimentally establish a library of nano-antennas. Our method brings an additional tool in the design of nano-antennas, which completes the existing simulation tools, by allowing to test all types of nano-antennas.
Ultra-low noise meta-mirrors with optical losses below 500 ppm
Authors: Dickmann Johannes , Shelling Neto Liam , Gaedtke Mika , Sauer Steffen , Nicolodi Daniele , Sterr Uwe , Kroker Stefanie
Published: October 2023

Interferometric experiments are often limited in sensitivity by the thermal noise of the mirrors. In particular, interferometric gravitational wave detectors and laser stabilization resonators can benefit from reduced mirror noise. We present results of experimental investigations on micro-structured mirrors (meta-mirrors) and hybrid etalon mirrors (meta-etalons) promising particularly low thermal noise. We show the first characterization of meta-etalons scattering and absorption losses, demonstrating optical losses below 500 ppm. This level of optical losses is sufficient for planning direct thermal noise measurement in dedicated optical cavity experiments. These measurements would be very important for validating the thermal noise predictions. We present our development toward the integration of meta-etalons in ultra-stable optical cavities.
High aspect ratio slanted grating replication process with low residual layer thickness
Authors: Kress Bernard , Pace Maria
Published: October 2023

Slanted subwavelength gra2ngs are used today in various products, especially as TIR couplers in Augmented Reality (AR) waveguides. Nano-Imprint Lithography (NIL) has been successfully used as a produc2on technique for such gra2ngs with periods down to 250nm, slants up to 45 degrees and aspect ra2o up to 2x. In order to propagate larger Field of View (FOV) in AR headsets, the refrac2ve index of the waveguide substrate needs to be large (1.9 to 2.0). NIL technologies typically produce a Residual Layer Thickness (RLT) of 100nm or more, requiring the index of the gra2ng resin to match the index of the substrate to prevent FOV clipping. This brings up many challenges such as TiO2 nanofiller migra2on during NIL process, scaRering and absorp2on in blue, and hard master / soT stamp combined degrada2ons. These challenges triggered a need for non-NIL techniques to mass produce such nanostructures, also at a lower cost. Avoiding mechanical contact between the master and the gra2ng material is desired, as costly masters would not deteriorate with volume produc2on. First experimental results are presented with aspect ra2o of 10x at 45deg slant and RLT below 3nm.
Bloch Surface Waves in Resonant Structures
Authors: Tang Zongyuan , Zambito Giorgio , Giordano Maria Caterina , Liu Yanjun , Buatier de Mongeot Francesco , Descrovi Emiliano
Published: October 2023

In this work, we make a step forward in the manipulation of light on the surface of one-dimensional photonic crystal through Bloch Surface Waves (BSW) within resonant structures of various types. Linear Fabry-Perot cavities eventually combined with diffraction gratings allow to directly couple BSW from free-space radiation. Design, fabrication and experimental characterization are provided.
Fabrication of nanometre sized gratings via ion irradiation
Authors: Kaufmann Johannes , Schrempel Frank , Zeitner Uwe
Published: October 2023

The damage caused by irradiation of crystalline material with ions results in localized volume changes. Here, swelling is utilized to fabricate nanostructured gratings with heights below 10 nm for extreme ultraviolet radiation. Irradiations were performed through a structured layer of photoresist shadowing parts of the sample from a broad ion beam. This enabled much shorter fabrication times than comparable direct write processes with a focussed ion beam. The study presents results from first systematic investigations regarding the fabrication of nanostructured gratings by irradiation of silicon with a broad beam of helium ions with energies of 30 keV. A smaller, scanned beam is used for comparison. Fluence was varied from 0.4 to 7.5×1016 ions/cm2. Fabricated structures were measured via atomic force microscopy. This yielded a controllable method to fabricate shallow gratings with heights in the range of 0 to 10 nm.
Design and fabrication of a vanadium dioxide-based actively switchable wire grid polarizer for near-infrared applications
Authors: Walther Markus , Siefke Thomas , Gerold Kristin , Zeitner Uwe D.
Published: October 2023

This study introduces an actively switchable wire grid polarizer exploiting the semiconductor-metal transition of vanadium dioxide. Operating at a near-infrared wavelength, the device features a SiO2 substrate with VO2 deposited by atomic layer deposition. We demonstrate the design using rigorous coupled wave analysis and show a viable fabrication route. Polarisation-resolved spectral transmission measurements show switching of the extinction ratio from 37.5 (on-state) to 1.6 (off-state). Despite observed deviations between measured and theoretical transmission values, the device shows potential in miniaturized imaging processes, polarization measurements, and ellipsometry.
Exciton fine structure of a single highly anisotropic CsPbBr3 nanocrystal
Authors: Guilloux Victor , Ghribi Amal , Boujdaria Kaïs , Barisien Thierry , Legrand Laurent , Lhuillier Emmanuel , Testelin Christophe , Chamarro Maria
Published: October 2023

We measured the photoluminescence (PL) of single CsPbBr3 nanocrystals (NCs) that have a highly anisotropic shape and orthorhombic crystal phase. As the thickness of these NCs is much more smaller than the other two dimensions, they are also called nanoplatelets (NPLs). We obtain PL spectra characterized by doublets separated in energy by about 2 meV in average and showing orthogonal and linearly polarized polar lines. We identified these doublets as the two bright-exciton states of the exciton fine structure contained in the plane of the NPLs. By a comparison between theory and experiments, we were able to obtain fundamental parameters as tetragonal and orthorhombic crystal field. We measured and analysed the time-resolved PL evolution as a function of temperature of small ensemble of NPLs. We thus succeed at framing the experimental value of the bright-dark exciton splitting (5-7meV) that is slightly smaller than the theoretical value.
Polarization-anisotropy of mid-infrared emission properties of Er3+ ions in YAlO3 crystal – INVITED
Authors: Nady Ahmed , Cassouret Florent , Loiko Pavel , Normani Simone , Braud Alain , Chen Weidong , Petrov Valentin , Sun Dunlu , Zhang Peixiong , Viana Bruno , Hideur Ammar , Camy Patrice
Published: October 2023

We report on a polarization-resolved study of mid-infrared emission properties of Er3+ ions in the orthorhombic YAlO3 crystal. For the 4I11/2 → 4I13/2 transition, σSE reaches 0.20×10-20 cm2 at 2919 nm (for light polarization E || c). Pump-induced polarization switching between the E || b and E || c eigen-states is observed in an 10 at.% Er:YAlO3 laser. Pumped by an Yb-fiber laser at 976 nm, this laser delivers 0.77 W at 2919 nm with a slope efficiency of 31.4% being close to the Stokes limit and a laser threshold of 33 mW.
Towards freeform manufacturing of ultra-low expansion glass optics
Authors: Benketaf Samuel , Torun Gözden , Bellouard Yves
Published: October 2023

Ultra-Low-Expansion glass (ULE®) has become an important technological enabler of advanced imaging for astronomy and for extreme-UV lithography. A major limitation though, is that ULE® cannot be poured from the fluid state unlike ZERODUR® which renders costly to produce large and/or complex shapes from it. Beside mirrors, optical components are rarely made of ULE® despite it sharing many properties of pure fused silica glass. Here we explore how femtosecond laser processing combined with laser induced reflow can be used to structure ULE® glass with the goal of producing miniature optical components. To fulfil optical roughness requirements, we adopt a strategy based on first producing elementary shapes, such as cubes or cylinders, that we further topologically transform into sphere, ellipsoids or curved surfaces, using a laser-reflow process. The structural modification of the glass matrix induced by the reflow were investigated using Raman spectroscopy. Our result points to a densification of the glass but no apparent sign of crystallization or devitrification. Furthermore, to understand whether the thermo-mechanical properties were affected or not, the thermal expansion coefficient was estimated using a dilatometry technic based on a pseudo-bimorph micro-cantilevers in a temperature-controlled chamber.
Exploration of responsive photonic arrays fabricated by two photon lithography
Authors: Qian Jing , Kolagatla Srikanth , Ryan Iseult , Florea Larisa , Delaney Colm , Bradley A. Louise
Published: October 2023

Responsive hydrogel photonic structures were fabricated using two-photon lithography. The design versatility of two-photon lithography provides for unprecedented manipulation of transmittance and reflectance spectra, producing distinct structural color. Hydrogel photonic structures have potential for wide range applications, in this instance we demonstrate examples of color transformation, reversible vapor sensing, and pH detection.
Crystalline waveguides with carbon nanomaterials for miniaturized pulsed lasers - INVITED
Authors: Bae Ji Eun , Rotermund Fabian
Published: October 2023

This presentation discusses the recent results on miniaturized pulsed solid-state lasers by utilizing femtosecond-laser inscribed crystalline channel waveguides and carbon-nanomaterial-based saturable absorbers. Based on optical characterization and optimization of the optical materials, integrated compact waveguide lasers present diverse pulsed operation regimes from Q-switching to continuous-wave mode-locking. Pulsing mechanism and various parameters in waveguide lasers are investigated to provide a basis for achieving higher performance of novel on-chip ultrafast lasers.
Innovative selective solar absorber for high vacuum flat panel
Authors: De Luca Daniela , Caldarelli Antonio , Gaudino Eliana , Strazzullo Paolo , Musto Marilena , Farooq Umar , Di Gennaro Emiliano , Russo Roberto
Published: October 2023

Selective Solar Absorbers (SSAs) are the critical element of high-vacuum flat plate collectors, as these are subject to elevated operating temperatures and thus experience high radiation losses. Here we design and optimize an SSA based on a multilayer design made of HfCx, Si3N4, and SiO2 layers. The structure of the proposed SSA has been optimized to maximize the solar-to-thermal energy conversion efficiency in high vacuum solar thermal panels working at 200 °C, reaching thermal emissivity values much lower than absorbers currently available on the market (<0.02 Vs >0.07) and obtaining unprecedented performances.
Mid-Infrared supercontinuum absorption spectroscopy beyond 7 µm based on free Arsenic chalcogenide fiber
Authors: Bizot Rémi , Désévédavy Frédéric , Lemière Arnaud , Serrano Esteban , Bailleul Damien , Strutynski Clément , Gadret Grégory , Mathey Pierre , Kibler Bertrand , Tiliouine Idris , Février Sébastien , Smektala Frédéric
Published: October 2023

Mid-Infrared methane (CH4) spectroscopy results were obtained in band III beyond 7 µm. To achieve this, the generation of supercontinuum covering the spectral range between 5 and 12 µm was realized by using purified chalcogenide optical fibers free of highly toxic elements such as arsenic and antimony. Besides a pumping with an optical parametric amplifier, an all fibered pumping scheme has also been investigated. In both configuration, supercontinuum absorption spectroscopy experiments have allowed for CH4 sensing, concentration as low as 14 ppm has been detected.
Nanocrystalline (Ho0.03Y0.97)2Hf2O7 luminophore for near- and mid-infrared
Authors: Vařák Petr , Mrázek Jan , Proboštová Jana
Published: October 2023

In recent years, a great scientific effort was dedicated to extending the operating range of lasers and amplifiers beyond the conventional 1.5 – 2.0 μm. Lasers operating in the mid-infrared range 2 – 5 μm find various applications as LIDARs, sensors, medicine, etc. However, the commonly used silica glass is unsuitable for emission above 2 μm due to the high phonon energy of the silica lattice, which completely quenches emission at longer wavelengths. The materials based on crystalline structure are perspective low-phonon materials for laser operation in the mid-infrared rage. In this contribution, we present the preparation and properties of a novel laser-active material based on holmium-doped yttrium-hafniate (Ho0.03Y0.97)2Hf2O7. The emission around 3 μm is successfully demonstrated.
Figure of merit for design of ε-near-zero metamaterials with enhanced Kerrtype nonlinearities
Authors: Dodici Francesca , Genchi Domenico , Cesca Tiziana , Mattei Giovanni
Published: October 2023

Metamaterials are artificial media designed to display properies going beyond those of ordinary materials. Particularly interesting are ε-near-zero (ENZ) media with real part of the permittivity going to zero in a certain spectral range. Examples of ENZ metamaterials are metal dielectric multilayers, which allow to tune the position of the ENZ wavelength depending on their composition and which have been found to have enhanced Kerr-type nonlinearities, i.e. nonlinear absorption and nonlinear refraction. In this work we define a figure of merit for the design of multilayer metamaterials with strong Kerr-type nonlinearities and compare our predictions with both simulations and experimental results.
Enhanced epsilon-near-zero structures for photonics
Authors: Calpe Roman , Koivurova Matias , Hakala Tommi K. , Turunen Jari
Published: October 2023

We present an experimental realization of a novel layered metamaterial we label enhanced epsilon-near-zero (eENZ). The structure is a stack of alternating thin films made of ENZ– and dielectric material and it can be designed for desired refractive/reflective properties by appropriately tuning the film thicknesses. The structure supports thin film resonances, guided modes and Ferrel-Berreman plasmon modes and the performance of the structure shows a large improvement to many currently available bulk ENZ materials. Additionally, we recently demonstrated the possible use of eENZ for coherence switching in lasers [1]. We demonstrate the design, fabrication and characterization of the optical properties of the eENZ stack and compare the measured transmission properties with transfer matrix method (TMM) simulations.
CaWO4:Yb3+,Tm3+ Crystals and SrAl2O4:Eu2+,Dy3+ Phosphors in Glass-Based Composites for Green Afterglow after NIR Excitation
Authors: Santos Magalhães Evellyn , Sedda Ahmed , Bondzior Bartosz. , Vuori Sami , Van der Heggen David , Smet Philippe F. , Lastusaari Mika , Petit Laeticia
Published: October 2023

Here, we present the preparation of composites with green persistent luminescence using melting process. The composites are phosphate glass (75NaPO3-25CaF2 and 90NaPO3-10NaF (in mol%)) with embedded phosphors: CaWO4: Yb3+, Tm3+ crystals with blue upconversion and SrAl2O4:Eu2+,Dy3+ with green persistent luminescence. Green persistent luminescence above 0.3 mcd/m2 can be seen for ~ 30 minutes after charging with 980 nm due to energy transfer between the blue upconverter crystals and the persistent luminescent phosphors. Challenges related to the fabrication of such composites are discussed.
Effective strategy for accessing the multi-pulse regime of mode-locked fiber lasers
Authors: Tchofo-Dinda Patrice , Malfondet Alix , Grelu Philippe , Millot Guy
Published: October 2023

We unveil a strategy for configuring mode-locked fiber lasers by means of a tunable bandpass filter, which allows multi-pulse structures to be generated without distortions in their intensity profiles, with significantly reduced pumping power levels.
Spatially entangled states of light in nonlinear waveguide arrays - INVITED
Authors: Raymond Arnault , Francesconi Saverio , Palomo José , Filloux Pascal , Morassi Martina , Lemaître Aristide , Raineri Fabrice , Amanti MariaI. , Ducci Sara , Baboux Florent
Published: October 2023

We demonstrate a nonlinear AlGaAs photonic chip generating biphotons with nonclassical spatial correlations. Photon pairs are generated by parametric down conversion in a waveguide array and simultaneously spread through quantum walks along the various waveguides. This concept implements a compact and versatile source of spatially entangled states, operating at room temperature and telecom wavelength, that could serve as a workbench for simulating condensed matter problems on-chip.
Predicting frequency comb structure in nonlinear optical fibre using a neural network
Authors: Boscolo Sonia , Dudley John M. , Finot Christophe
Published: October 2023

We deploy a neural network to predict the spectro-temporal evolution of simple sinusoidal temporal modulations upon propagation in a nonlinear dispersive fibre. Thanks to the speed of the neural network, we can efficiently scan the input parameter space for the generation of on-demand frequency combs or the occurrence of substantial spectral/temporal focusing.
4-Field spontaneous symmetry breakings in photonic molecules
Authors: Ghosh Alekhya , Hill Lewis , Oppo Gian-Luca , Del’Haye Pascal
Published: October 2023

We present in this work a study of 4-field symmetry breakings in two photonic molecule structures consisting of two identical microresonators with distinct coupling arrangements. Mediated by the Kerr-interaction, the systems also display different 2-field symmetry breakings, periodic switching and chaos. The wide range of nonlinear optical dynamics makes the system ideal for all-optical switching, optical memories, telecommunication systems, polarization controllers and integrated photonic sensors.
Polygons of quantized vortices in nonlinear photonic waveguides
Authors: Michinel Humberto , Paredes Angel , Salgueiro José Ramón
Published: October 2023

In a nonlinear optical waveguide with defocusing Kerr-type nonlinearity, we discuss the existence of a type of stationary nonlinear waves with propagation-invariant density profiles, consisting of vortices located at the vertices of a regular polygon with or without an anti-vortex at its center. These polygons rotate around the center of the system and we provide approximate expressions for their angular velocity. We have computed the evolution of the vortex structures and discuss their stability and the fate of the instabilities that can unravel the regular polygon configurations. Such instabilities can be driven by the instability of the vortices themselves, by vortex-antivortex annihilation or by the eventual breaking of the symmetry due to the motion of the vortices.
Large period spiking andburstingin anexcitable system with memory
Authors: Braeckeveldt Bertrand , Peters Kevin , Verdonschot Bart , Rodriguez Said , Maes Bjorn
Published: October 2023

Excitability in dynamical systems refers to the ability to transition from a resting stationary state to a spiking state when a parameter is varied. It is the mechanism behind spike generation in neurons. Optical non-linear resonators can be excitable systems, but they usually present a fast response compared to neuronal systems, and they prove difficult to observe experimentally. We propose investigating optical resonators with delayed Kerr effects, specifically in two different geometries: an oil-filled single-mode cavity with thermo-optical nonlinearity, and two coupled, symmetrically driven cavities. When the Kerr effect is delayed, even a single cavity exhibits excitability. However, we show that it suffers from limitations on the thermo-optical relaxation time in order to be realized experimentally. We overcome these limitations using the geometry with coupled cavities, where the thermo-optical relaxation time acts as a memory. This slow variable enables to tailor the spiking frequency and it mimics neuronal behaviours by enabling large-period spiking.
Single-mode operated multimode AlGaAs-on-insulator microring resonators for Kerr comb generation
Authors: Ye Chaochao , Liu Yang , Zhou Yueguang , Zheng Yi , Kim Chanju , Yvind Kresten , Pu Minhao
Published: October 2023

We present a tapered coupler design to achieve single-mode operation in multimode microring resonators and experimentally demonstrate Kerr comb generation in a high-Q, single-mode operated AlGaAs-on-insulator multimode microring resonator.
Broadband and fast frequency chirped FTIR spectroscopy with strongly modulated quantum cascade lasers
Authors: Cargioli Alessio , Piciocchi Diego , Bertrand Mathieu , Maulini Richard , Blaser Stéphane , Gresch Tobias , Muller Antoine , Faist Jérôme
Published: October 2023

While the opportunity to perform fast and broadband spectroscopy in the Mid-IR portion of the electromagnetic spectrum is very appealing, it requires the use of compatible light-sources. Here, we strongly modulate a Mid-Infrared Quantum Cascade Laser at a frequency in the RF domain, which is low compared to the natural repetition frequency of the device. In this way, we demonstrate that it is possible to obtain an emission bandwidth of up to 250cm-1. Finally, we employ it as a light source in an FTIR based on a rotational delay line, performing fast and broadband FTIR spectroscopy.
Feasibility of dual comb spectroscopy in the UV range using a free-running, bidirectional ring titanium sapphire laser
Authors: Feuvrier Abel , Pivard Clément , Morville Jérôme , Rairoux Patrick , Galtier Sandrine
Published: October 2023

We show that our developed free-running, bidirectional ring Ti:Sa laser cavity meets the requirements for Dual Comb Spectroscopy in the UV range (UV-DCS). Two counter-propagative frequency combs with slightly different repetition rate are generated in such a cavity and we show quantitatively that this repetition rate difference can be explained by the self-steepening effect. Molecular absorption lines of the O2 A-band centered around 760~nm are measured with a 1,5 GHz spectral resolution, demonstrating that the mutual coherence of the two combs allows GHz-resolution DCS measurements. Moreover, we demonstrate that the generated output peak power allows for efficient second harmonic generation (SHG), in the scope of developing laboratory and open-path UV-DCS experiments.
Direct measurement of an ultrafast sub-bandwidth-limited signal in mid-infrared quantum cascade lasers
Authors: Schneider Barbara , Dikopoldsev Alexander , Täschler Philipp , Kapsalidis Filippos , Beck Mattias , Faist Jérôme
Published: October 2023

Frequency comb lasers with fast gain recovery times naturally favor the emission of frequency mod-ulated periodic signals, which are useful for multiple applications in spectroscopy and communications. Models and phase measurements predict an ultrashort strong intensity spike at the instantaneous frequency discontinuity of the cavity cycle. Here we experimentally study the ultrashort spike of fast-gain frequency modulated combs through direct upconversion sampling, and measure a width below that of a transform-limited pulse. Specifi-cally, we demonstrate a mid-infrared quantum cascade laser which inherently lases in a frequency modulated comb and produces a spike with full-width at half-maximum below 600 fs, which is below the Fourier-limit derived from the corresponding spectrum. We believe these ultrashort spikes can be highly beneficial for sub-bandwidth time domain measurements. Using mean-field theory based simulations, we confirm the occurrence of such features as well as further optimize our system for going even further below the Fourier-limit.
Ultrafast Yb:CALGO laser oscillator based on cross-polarization pumping with a cost-efficient multi-mode diode
Authors: Trawi Firas , Drs Jakub , Müller Michael , Hamrouni Marin , Modsching Norbert , Wittwer Valentin J. , Südmeyer Thomas
Published: October 2023

We demonstrate a multimode diode-pumped Yb:CALGO laser oscillator based on bandwidth-optimized cross-polarization pumping targeting sub-30-fs operation. In our first proof of principle experiment we achieved mode-locked operation at 83 MHz repetition rate with 0.4 W of average power and a 33-nm-bandwidth optical spectrum supporting sub-40-fs pulses. This concept offers a simple and cost-efficient alternative to green-pumped Ti:sapphire lasers.
Ultra-high phase-locked harmonic generation from magnetic transversal confinement of electrons
Authors: Plaja Luis , Martín-Hernández Rodrigo , Hu Hongtao , Baltuska Andrius , Hernández-García Carlos
Published: October 2023

The technological refinements on high-power laser systems of Petawatt class unveil scenarios for light-matter interaction beyond the laser-plasma perspective. In this contribution we explore the possibility of assisting high-harmonic generation (HHG) with the strong magnetic field associated with one of those intense sources. Recently, there has been an interest in developing schemes to employ intense laser beams to define spatial volumes in which strong magnetic fields are found isolated from the electric field. In this conditions, the magnetic field can be used to assist the harmonic generation from atoms from standard drivers. We demonstrate that, using the proper interaction geometry, the magnetic field confines the transversal dynamics of the con-tinuum electrons allowing, on one side, to enhance the efficiency of the electron rescattering that produces the harmonic radiation and, on the other side, to excite the electron transverse dynamics and to convert this energy into phase-locked harmonic photons of few hundreds of eV.
High-precision phase plate for targeted generation of pseudorandom femtosecond pulses
Authors: Veselá Petra , Junek Jiří , Žídek Karel
Published: October 2023

The targeted generation of fs pulses is essential for a variety of applications and it is routinely carried out by 4f pulse shapers. However, this seemingly simple task is complicated by hidden experimental limitations, such as modulator crosstalk or pixelation. We present an approach to overcome this issue by using a high-precision phase plate with a phase change characterized with λ/500 precision. We generated pseudorandom pulses using a 4f pulse shaper by using a structured PMMA plate with the high-precision predefined shape made by the SPDT machine. We study the accuracy, reproducibility, as well as the sufficiency, and limits of the method. The generated pulses are characterized using the FROG method. The reconstructed pulses’ shapes and their spectral phases are compared to the results of simulations.
Featurization of Ultrafast Expansion and Geometrical Properties of Heterogeneous Colliding Plasmas
Authors: Al-Juboori Haider M. , McCormack Tom
Published: October 2023

Numerous fields of research and industry have undergone revolutionary change because of the unique characteristics of ultrashort laser pulses. Moreover, the ultrafast imaging sensors, such as ICCD technique, can help to understand the ionization features and expansion properties of colliding laser-induced plasma (CLPP) and related stagnation layer (S.L.) geometry. In this work, the effort will be focused on CLPP experiments from two seeds of heterogeneous elements. The research’s goal is to analyse the geometrical development of the colliding plasma, the temporal evolution of plume composition features and its associated characteristics. The expansion velocity and forward propagation range (FPR) of the stagnation layer in a nanosecond scale—both of which have been discovered. The ultrafast imaging results give the sight and explain the possibilities of extant technologies that can help to re-engineer the plasma characteristics for the next generation of lithography applications or new selective physical concepts.
HIBISCUS: Simulator for the development of control strategies for coherent beam combining lasers with PISTIL technique
Authors: Rousseaux Thomas , Primot Jérôme , Chanteloup Jean-Christophe , Rouzé Bastien , Bellanger Cindy
Published: October 2023

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