bluuebunny/crossref_metadata_2025 huggingface dataset:
Mode Profile Modification of H Beam-Implanted Waveguides Using UV Processing
Authors: Canning J. , von Bibra M. L. , Roberts A.
Published: December 2022

UV photosensitivity in planar waveguides has primarily concentrated on the generation of sufficient oxygen-deficient centres using germanosilicate glass. There exists a wide range of methods fo fabricating such glasses, all with varying degrees of photosensitivity. Empirically, in planar waveguide at least, the degree of photosensitivity seems to be closely related to the defect induced losses such a increased Rayleigh scattering. For example, waveguides fabricated using flame hydrolysis exhibit very low propagation losses indicating a high level of purity of the glass. Consequently, this material requires sensitisation with hydrogen in order to achieve sizeable index changes with uv irradiation [1]. On the other hand, recent developments have allowed the demonstration of ultra-strong Bragg gratings in unsensitised PECVD-based glass [2], although at the expense of significantly higher propagation losses. A somewhat more impressive demonstration of photosensitivity has been the demonstration of direct waveguide writing with a mercury lamp in organically-derived glass using sol-gel methods [3]. By incorporating organic components into the glass silica polymer matrix, index change is achieved through polymerization of the organic ends which is a substantially different mechanism to that relying upon oxygen deficient centre absorptions. Low propagation losses, whilst maintaining a large photosensitivity, have been achieved this way. In addition to these materials, strong uv photosensitivity has also been observed in ion beam implanted material, mainly with Si2+ and Ge3+ implanted germanosilicate glass [4,5] although some work has been reported on changes in the uv spectra of H+ implanted germanosilicate waveguides [6].
Large refractive index changes observed in silicon implanted silica exposed to high cumulative doses of ArF laser light
Authors: Verhaegen M. , Brebner J.L. , Albert J.
Published: December 2022

Used extensively in optical fibers technology, the change in refractive index produced by ultraviolet light in photosenstive silicate glasses is still not fully understood. Ion implantation is the only technique able to make photosensitive pure silica waveguides by the introduction of bleachable color centers and compaction of the matrix. After 100 pulses of 100mJ/cm2 of ArF bleaching, changes in the refractive index were found to be in good quantitative agreement with the changes in absorption of the bands induced by implantation between 5 and 8 eV. Index of refraction and absorption measurements of higher cumulative doses of ArF laser light as well as a Kramers-Kronig analysis are reported.
Relationship between Ge lone pair center and Ge electron center
Authors: Awazu Koichi , Morishita Yuichi , Muta Ken-ichi
Published: December 2022

Recently, material science on Bragg gratings are well studied, yet, there is still much room for investigation. For example, whether the 5eV optical absorption band in Ge doped silica is essential for the photo-sensitivity or not is highly debatable point. One of the reasons why photo-sensitive phenomena are complicate is that different light sources and samples have been used in each reports. Even if laser power for excitation is very week, two-photon process might not be negligible. For instance, Ge electron center (GEC)1 is induced in the Ge-doped silica with UV illumination at 5eV by KrF excimer laser, in contrast, it is not observed in the sample illuminated at 5eV using Xe/Hg discharged lamp.2 In this article, relationship between intensity at 5eV and GEC was examined. Secondly, relation between GEC generation and excitation photon energy was also examined.
Temperature dependence of UV-induced defects in thulium-doped ZBLAN fibers
Authors: Laperle Pierre , Vallée Réal , Chandonnet Alain , LaRochelle Sophie
Published: December 2022

The thulium-doped ZBLAN fiber has been identified as a promising candidate for the generation of coherent blue radiation.1 Yet Tm-ZBLAN blue fiber lasers have been shown to suffer from a progressive deterioration of their performances as they operate for several hours, apparently because of an increase in the absorption of the fiber at the laser wavelength. This problem, which has been clearly observed with a pumping source at 1.12 μm, is thought to be related to the formation of defect centers induced by UV radiation generated as a by-product of the upconversion process occuring in the thulium ions.2,3 The induced absorption can be bleached by exposure to visible light. However, the observed photobleaching is only temporary and a permanent recovery of the pristine condition of the glass can only be achieved by a thermal treatment. Moreover, the darkening as well as the bleaching processes taking place in these fibers have been shown to be well described by stretched-exponential (S-E) functions.4 Thus, it appears that a better understanding of these defects, which is crucial for the development of practical Tm-ZBLAN blue fiber lasers, relies on the study of their UV-induced formation as well as their temperature dependence. We report on these two mechanisms and, through an S-E analysis of the temperature dependence of the defects, show to what extent they are related.
The origin of photoinduced anisotropy in germanium sulfide based glasses.
Authors: Tikhomirov V. , Hertogen P. , Krasteva V. , Adriaenssens G. , Sigel G.
Published: December 2022

Metastable photoinduced anisotropy (PA) generated by linearly polarized sub-bandgap light in Pr-doped Ge-S-I glasses is reported. A PA minimum is observed in undoped Ge34.5S55.5I10 composition. PA increases with S content in S-rich glasses. PA increases with Ge content at a constant I content in Ge-rich glasses, while addition of I at a constant S/Ge ratio in Ge-rich glasses decreases the PA. The addition of Pr to about 1000 ppm increases PA in Ge-rich glasses, if no Pr-clustering occurs. The explanation of these compositional trends is based on the coexistence of three different molecular phases (structural units) in these glasses, with their relative contribution varying with varying composition. Microscopic models are proposed for diamagnetic defect centers responsible for PA in S-rich, Ge-rich and stoichiometric glasses.
What Can Topological Models Tell Us About Glass Structure and Properties?
Authors: Hobbs Linn W.
Published: December 2022

Atomic arrangements in condensed matter partition three-dimensional space into polyhedra whose edges are interatomic vectors. These polyhedra, formally known as void polytopes, fill (tesselate) space, and their identity and arrangement can provide one description of a given atomic arrangement (Figure 1a) [1]. Other tessellations associated with space-filling of random structures are Voronoi polyhedral cells [2] and their dual the Delauney network [3]. These tessellations are relatively intuitive in two dimensions, but considerably more complex in three-dimensions—for example in tetrahedral networks like SiO2—where a set of as many as 126 void polyhedra may be required to model interstitial space [1]. Because many arrangements favor particular coordination of one atom by others, owing to bond orbital, radius ratio, or local electrostatic neutrality considerations, discrete coordination polyhedra comprise a subset of the possible void polytopes, and the structure may be described by the way in which coordination polyhedra are connected together and fill space by defining the remaining void polytopes. Space filling by connected structural units was a favorite description tool of early crystal chemists [4], and in fact the connectivity of such structural polytopes (number of polytopes sharing vertices, edges and faces) has been shown to correlate with glass-forming ability and extendability of aperiodic networks [5] and to govern the amorphizability of crystalline solids [6].
Fibre Grating Devices for Telecommunications Applications
Authors: Sansonetti P.
Published: December 2022

Photosentivity occuring in germanium-doped silica [1] allows, through UV side holography [2], the simple and straightforward realization of permanent refractive index gratings in optical fibres. Low cost, low loss and very efficient all fibre filtering or multiplexing devices can therefore be realized, with extreme interest for future Transparent Optical Networks based on Wavelength Division Multiplexing (WDM), including chirped grating Chromatic Dispersion Compensator allowing to cope with bit rate increase per channel.
270 nm absorption and 432 nm luminescence bands in doped silica glasses
Authors: Poumellec B. , Mashinsky V.M.
Published: December 2022

There are a lot of structure defects known more or less in pure and doped silica[1]. They appear either in absorption or in fluorescence or also in EPR. In this paper, we are interested in the occurrence of 270 nm absorption and excitation band. This band was mentioned first in a paper in 1982[2]. In this paper, in synthetic GeO2-SiO2 glass containing 0.2 wt% of Ge, the authors have found 270 nm excitation band associated with 435 nm luminescence band. They note that Garrino-Canina[3] have seen a luminescence at 435 nm band but in a much less pure sample. They associate the GeO defect to this band. One year later, Gebala[4] has noticed a 270 nm excitation and 430 nm luminescence band in Ge-P-SiO2. He has associated this to Ge2+ in octahedral coordination.
Comparing the effect for second harmonic generation by electron beam scanning and α-beam irradiating on glass
Authors: Qiu Mingxin , Pi F. , Orriols G.
Published: December 2022

We study the mechanism of second harmonics generation in lead silica scanned with an electron beam. Firstly, we found to use a-beam irradiating on either silica or lead silica there is not any second harmonic signal. The electric field in the layer can not be produced by positive particle. Secondly we change lead component, 47%, 51%, 61% and 71% by using F2, SF2, SF11, and ZF7 lead silica, respectively. The second harmonic signal increases linearly with the lead ratio. Thirdly we found there is a saturated signal at an optimum scanning values of total electron charge. This is due to the threshold of inner electric field beneath the glass surface to cause breakdown. Fourthly we obtain the coefficients for Bohr-Bethe electron penetration formula in lead silica.
Periodic structures in photo-thermo-refractive glasses induced by homogeneous UV irradiation
Authors: Glebov L. , Smirnov V.
Published: December 2022

Samples of photo-thermo-refractive glasses were exposed to a homogeneous collimated beam of a He-Cd laser at 325 nm. A refractive index change is observed in the exposed glass upon thermodevelopment due to photoinduced crystallization. A periodic structure was observed inside this exposed area by optical microscopy. This structure is a system of parallel continuous aligned filaments having widths of ten's of microns oriented along the direction of light propagation. Variation of incident light polarization direction does not effect the resulting structure.
Photosensitive thin film materials and devices
Authors: Simmons-Potter K. , Potter B.G. , Sinclair M.B. , Meister D.C.
Published: December 2022

Planarization of photosensitive device technology promises to significantly expand the application options for this type of material. Current use of hydrogen techniques have successfully produced strongly photosensitive thin-films, but require complex manufacturing processes and preclude in-situ writing of optical interconnects. We will report on the production of highly photosensitive thin films, without the use of post-deposition processing, which promise compatibility and integrability with III-V and Si processing. We will demonstrate a number of device structures with unique optical functionality in our films.
Processing-induced defects in optical waveguide materials
Authors: Sigel G.H. , Lee J.W.
Published: December 2022

There is continuing concern with regard to the impact of fiber drawing conditions on the optical properties of silica as both preform sizes as well as drawing speeds increase to meet the demands of production. This paper reports recent work conducted on fiber drawing induced defects using our fabrication facility. Specific topics to be presented include the spatial distribution of defect centers generated in synthetic silica fibers, the photosensitivity of drawn fibers to ultraviolet light, photoluminescence of fibers compared to preforms or bulk rods from which they are drawn and the impact of accelerated cooling on defect center generation in silica fibers. These studies have been conducted over a variety of drawing conditions including drawing speed, drawing temperature and fiber tension.
Report on second harmonic generation in soda-lime glass and relative new phenomena
Authors: Qiu Mingxin , Pi F. , Orriols G. , Bibiche M.
Published: December 2022

We report the second-harmonic generation in soda-lime glass for the first time. During poling some white material coated on the glass surface on cathode side. By ESCA analysis the white material is mainly a compound of sodium, which is the first evidence to prove the supposition that sodium captions move towards the cathode in the glass during the poling. This may help us to understand the mechanism of second-harmonic generation in the poled glass. We found the signal of second harmonics decreases with time after poling and the damping rate depends on the surrounding temperature. The signal decay in fact is the decay of the electric field and the charged particle inside glass. There is a residual signal after damping for one week, which does not change for months. The residual signal depends on the poling temperature. Thus we have to assume that there are two kinds of negative particles in the poling process in soda-lime glass.
Rare earth doped PZG fluoride glass channel waveguides: spectroscopy and signal amplification
Authors: Lebrasseur E.C. , Jacquier B. , Boulard B. , Rimet R.
Published: December 2022

Laser spectroscopy of R.E. doped fluoride waveguides elaborated by PVD technique on ZBLAN or CaF2 substrate is presented. Channel waveguides of the PZG composition were obtained photolithography process on the substrate before deposition. Nd3+ fluorescence at 1.5 μm as well as erbium fluorescence at 1.55 μm are reported including decay time dependence with R.E. concentration. Finally, we have measured a signal amplification of 3.8 dB/ cm at 1.05 μm in a 1 at% Nd-doped PZG waveguide.
Fluorescent cooling of ytterbium-doped heavy metal fluoride hosts
Authors: Murtagh M.T. , Sigel G.H. , Fajardo J.C. , Edwards B.C. , Epstein R.I.
Published: December 2022

As first discussed by Pringsheim in 1929, continual cooling of a material may occur via anti- Stokes luminescence. However, not until recently was net cooling actually observed experimentally in a solid. By pumping Yb3+ to the lower Stark levels of the 2F5/2 manifold, followed by population redistribution across this manifold and fluorescence to the ground state, removal of heat from a ZBLAN-derived fluoride host was achieved. The Yb-doped ZBLANP host demonstrated a temperature drop of 0.33 K at 1008 nm via infrared evaluation. Photothermal deflection spectroscopy (PTDS) was employed to measure the relative cooling efficiency (DC laser power to cooling power), which was determined to be 2.03%. Due to constraints on the doping levels in ZBLAN-derived hosts, other high rare earth concentration fluoride hosts are presently being investigated as potential coolers. BIZYT-derived hosts, with Yb concentrations as high as 26%, have been shown to contain similar spectral characteristics to that of ZBLAN, and thus sufficient spectral overlap for anti-Stokes fluorescent behavior. In general, the potential for high levels of net cooling in Yb-doped fluoride glasses makes these hosts attractive candidates for the development of a first- generation optical cryocooler for astronomical remote sensing applications.
Possibilities of 119-Tin NMR for the characterization of glasses
Authors: Braun M. , Jäger C. , Ehrt D. , Daniel A.
Published: December 2022

Besides the study of inorganic oxide glasses using traditional MAS NMR of abundant nuclei (e.g. phosphorus, aluminium) the measurement of less common nuclei (e.g. Tin) provide important structural information. The experimental setup is more complicated due to the low natural abundance (8.5%), large chemical shift anisotropies (up to 1000 ppm), and long relaxation times of these nuclei (up to 500 s). Results will be presented for 119-Tin MAS NMR measurements of P2O5-SnO2 glasses. We have found a large change of Tg and phosphorus coordination at different Tin content.
Residual stresses due to refractory inclusions in silica glass
Authors: Wissuchek D.J.
Published: December 2022

Residual stresses due to thermal expansion mismatch for refractory particles on high purity silica glass were studied. Finite element analysis was used to determine the stresses around ZrO2, Cr3O4, SiC and graphite particles in contact with a SiO2 substrate. Results were obtained for both fully and half submerged particles. Results were compared to existing analytical models for fully submerged particles where applicable. Effects of particle aspect ratio for elongated particles were studied. ZrO2, Cr3O4 and SiC were modeled as isotropic materials. All exhibited tensile radial stresses, with ZrO2 displaying the highest stress levels. The stresses at the SiO2 surface reached a maximum a short distance from the particle/matrix interface. Peak radial stress increased with increasing particle aspect ratio. Maximum tensile stress for elongated particles was located at the tip of the particle, corresponding to fracture origins noted for these particles. Graphite particles were modeled as anisotropic structures and the stresses were determined for different crystalline orientations. Unlike the other refractories, the maximum tensile stress for a graphite particle in one of its possible orientations was located at the edge of the particle. This corresponds to fracture origins noted on silica glass with graphite particle surface flaws. The stress field results are discussed in a fracture mechanics framework, and the effect of residual stress on material reliability is presented.
Direct characterization of ultraviolet-light-induced refractive index structures by scanning near-field optical microscopy
Authors: Svalgaard M. , Madsen S. , Hvam J. M. , Kristensen M.
Published: December 2022

In recent years high-resolution microscopy has experienced the application of probe-based scanning techniques such as the scanning near field optical microscope1 (SNOM). In contrast to conventional optical far-field imaging, the SNOM utilizes a non-propagating (evanescent) nearfield, whereby the achievable lateral resolution overcomes the far-field diffraction limit of λ/2 where λ is the wavelength of the imaging light.
Fiber Bragg Gratings With Reflectivity > 97% Fabricated Through Polymer Jacket Using Near-UV Light
Authors: Starodubov D. S. , Grubsky V. , Feinberg J. , Dianov E. M. , Semjonov S. L. , Guryanov A. N. , Vechkanov N. N.
Published: December 2022

Fiber Bragg gratings are important components for a variety of applications including WDM communications, fiber lasers and fiber sensors. An expensive and time consuming step for Bragg grating fabrication is the removal of the protective polymer coating of the fiber in order to expose the photosensitive fiber core [1]. Removing the fiber’s polymer jacket and exposing the glass cladding surface to the atmosphere and UV light also substantially decreases the strength of the fiber [2,3].
Fundamental Line Broadening Mechanisms of Single-Frequency CW (GaAl) As Diode Lasers*
Authors: Welford D. , Mooradian A.
Published: December 2022

We report here a study of the fundamental mechanisms which account for the spectral linewidth of cw single-frequency (GaAl)As diode lasers. The experiments were carried out on a number of Mitsubishi transverse-junction-stripe (TJS) and Hitachi channel-substrate-planar (CSP) lasers at 273, 195 and 77 K. The linewidths shown in Fig. 1 were observed to increase linearly with reciprocal output power1 at all temperatures. However, a power-independent contribution2 to the laser linewidth was also observed which increased in magnitude with decreasing temperature.
Frequency Stabilized Single Axial Mode Nd:YAG Oscillator
Authors: Long Sun Yun , Byer Robert L.
Published: December 2022

Single frequency Nd:YAG is potentially a very useful laser source for remote wind velocity measurements by coherent LIDAR Doppler velocimetry.1 The measurements require a laser source with less than 1 MHz linewidth, pulse energy and widths of 300 mJ at 1 psec and local oscillator power of 1-10 milliwatts for heterodyne detection of the return signal. During the past year we have pursued the design of a single axial mode Nd:YAG oscillator with the goal of demonstrating a frequency stability adequate for wind velocity measurements.
Large Optical Nonlinearities in Room-Temperature GaAs-GaAlAs Multiple Quantum Well Structures
Authors: Chemla D. S. , Miller D. A. B. , Smith P. W. , Gossard A. C. , Tsang W. T.
Published: December 2022

The development of digital optical switching and signal processing devices is strongly dependent on the availability of suitable nonlinear optical materials. In this paper we report what we believe to be a major step in this direction - the demonstration of extremely large optical nonlinearities at room-temperature in GaAs-GaAlAs multiple quantum well (MQW) structures. Previous demonstrations of comparable nonlinearities utilized cooled semiconductors1.
Fabry-Perot Photothermal Trace Detection
Authors: Carnpillo A. J. , Petuchowski S. J. , Davis Christopher C. , Lin H-B.
Published: December 2022

The photothermal effect constitutes the basis of a number of schemes to measure very small light absorptions. Examples include phase fluctuation optical heterodyne (PFLOH) detection1 and thermal lensing. The former has proven useful in sensitive trace-gas detection schemes2, 3 and has been shown to be competitive with photoacoustic detection. PFLOH detection monitors the refractive index change by placing the heated sample in a sensitive Machr-Zehnder interferometer employing a stable single frequency helium neon laser.
Scaling Studies for the XeCl Discharge Laser, Operation of a 75 cm2 Aperture Laser
Authors: Wexler B. L. , Djeu N. , Burnham R.
Published: December 2022

There are a number of potential applications of excimer lasers which require energies significantly higher than those achieved to date in discharge-pumped devices. Because of the apparent specific energy limitation on the order of 1 Joule/1iter-atmosphere and kinetics limitations on the pressure, output energies of tens of Joules or greater will require large volume devices. We are presently studying the problems of scaling up these lasers and as a first step have constructed a XeCl discharge laser with 3 liter active volume.
Laser Photodeposited Metal Films: Stimulated Surface Plasma Waves And Growth of Grating Structures*
Authors: Brueck S. R. J. , Ehrlich D. J.
Published: December 2022

We demonstrate that surface plasma wave (SPW) effects result in the growth of high spatial frequency surface relief in thin photochemically deposited Cd films. Initially a weak SPW is excited by surface roughness-induced scattering from the incident field, the spatial modulation of the optical intensity resulting from the interference between the incident wave and the SPW promotes the growth of a periodic (ripple) structure which increases the scattering into the SPW. There is a positive gain coefficient increasing both the amplitude of the film structure and SPW intensity for spatial frequencies ranging from approximately the incident light wavevector to the SPW wavevector. The process, which is analogous to stimulated Raman scattering where the grating structure plays the role of the material excitation and the SPW corresponds to the Stokes beam, is the first demonstration of an exponentially growing instability involving surface electromagnetic waves.
Off-axis holographic optical element fabrication for practical near-eye displays: Uniformity improvement with optimized angular and wavelength selectivity
Authors: Hwang Leehwan , Hur Gitaek , Kim Jungho , Getnet Philippe , Kwon Soonchul , Lee Seunghyun
Published: December 2022

Transparent thin-film holographic optical elements (HOE) are suitable for implementing extended screens and depth cues for small form factor devices like near-eye displays (NED). Here, optimized data for a practical NED fabrication is presented based on the analysis of the uniformity, angle selectivity, and wavelength selectivity of an HOE reconstructed image applied to an NED system.
Structuring the far-field transmission from multimodal optical fibers using wavefront engineering
Authors: Collard Liam , Pisano Filippo , Pisanello Marco , Balena Antonio , De Vittorio Massimo , Pisanello Ferruccio
Published: December 2022

We describe a method to control intensity distribution of the far-field transmission of a multimode fiber [1] demonstrating how the output wavevector could be tuned potentially enabling holographic manipulation of plasmonic resonances at the output.
A Large Field-of-view Imaging and Stitching Method Using a Risley-prism-embedded Camera
Authors: Pan Weidong , Li Anhu
Published: December 2022

We propose a large field-of-view, high-resolution imaging method. A Risley-prism-embedded camera captures different regions of interest of objects from multiple viewpoints. In addition, a fast matching method is proposed to achieve efficient image stitching.
ADMM Based Regularized Optimization for Reconstruction of Digital In-line Holography
Authors: Shaji Athira , Sheeja M. K.
Published: December 2022

Compressed sensing is effective in twin image removal of in-line holograms, but has slower convergence and higher computational time. Proposed method suppresses twin images by solving an inverse problem using ADMM and offers better convergence.
Advances in Automated Disease Identification with Digital Holography [Plenary Address]
Authors: Javidi Bahram
Published: December 2022

This Plenary is an overview of advances in automated disease identification with low-cost field portable digital holographic systems integrated with dedicated algorithms. Recent applications of digital holography and dedicated algorithms for rapid COVID-19 detection will be presented.
Phase Retrieval for Terahertz Holography with Physics-Informed Deep Learning
Authors: Xiang Mingjun , Wang Lingxiao , Sha Yu , Yuan Hui , Zhou Kai , Roskos Hartmut G.
Published: December 2022

Two novel phase retrieval methods for THz holography based on physics-informed deep learning are presented. They employ unsupervised learning and supervised learning based on the MNIST dataset, respectively.
On the anisotropy of decorrelation noise in digital holographic interferometry
Authors: Meteyer Erwan , Pezerat Charles , Picart Pascal
Published: December 2022

This paper discusses on the anisotropy of decorrelation noise in digital holographic interferometry. Theory is supported by experimental results demonstrating the noise is anisotropic.
Investigation of distortion and bias in holographic imaging of acoustic fields
Authors: Hassad Saoucene , Ferria Kouider , Bouamama Larbi , Picart Pascal
Published: December 2022

This paper discusses on distortion and bias in digital holographic imaging applied to the visualisation of acoustic fields. Distortion due to exposure time and bias due to the propagation of the laser beam in the acoustic field are investigated.
Space Bandwidth Product Enhancement of Holographic Display using High Diffraction Order
Authors: Jo Youngjin , Yoo Dongheon , Lee Byoungho
Published: December 2022

We propose a holographic display that expands the space-bandwidth product to the region of high-order diffraction based on temporal multiplexing technique. The simulation results show the bandwidth expansion by nine times with high image quality.
Deep neural network and its training strategy for converting computer-generated hologram between different display systems
Authors: Lee Juhyun , Lee Byoungho
Published: December 2022

We propose a deep learning method to convert the given hologram for a display system to a new one for another system. The proposed method can be applied to adapt holograms to any component changes of different systems. In this paper, we set different wavelength of the light source for the original and target display system. Convolutional neural network is designed, and artificial hologram dataset is used for training. Numerically reconstructed images of the converted holograms are shown.
Macroscopic Optical Coherence Tomography Imaging Enabled 3D Viewing and Printing of Artworks
Authors: Zhou Xingyu , In Darlene , Xiong Xinchang , Yang Kunze , Chen Xing , Bruhn Heather McCune , Liu Xuan , Yang Yi
Published: December 2022

This paper demonstrates the applications of using OCT to acquire the surface profile of artworks and render the 3D volumetric data into standard virtual reality (VR), augmented reality (AR), and 3D printing formats.
Deep Learning based Segmentation of Optical Coherence Tomographic Images of Human Saphenous Varicose Vein
Authors: Viqar Maryam , Madjarova Violeta , Yadav Amit Kumar , Pashkuleva Desislava , Machikhin Alexander S.
Published: December 2022

Deep-learning based segmentation model is proposed for Optical Coherence Tomography images of human varicose vein based on the U-Net model employing atrous convolution with residual blocks, which gives an accuracy of 0.9932.
Synthesis of nano-optical elements for zero-order diffraction 3D imaging
Authors: Goncharsky Anton , Durlevich Svyatoslav
Published: December 2022

A method is proposed to compute and synthesize a microrelief to produce a new nano-optical element for forming 3D images with full parallax at the zero order of diffraction. The synthesis of nano-optical elements requires the use of multilevel structures. Optical security elements that produce the new security feature are synthesized using electron-beam lithography. The accuracy of microrelief formation is 10 nanometres in terms of depth. A sample optical security element is manufactured, which when illuminated by white light, forms a 3D image at the zero order of diffraction. The new optical security feature is easy to control visually, safely protected against counterfeiting, and designed to protect banknotes, documents, ID cards, etc.
Linear diattenuation sensitive lens-free holographic microscope
Authors: Lopera Maria J. , Trujillo Carlos
Published: December 2022

We report the implementation of the simplest lens-free holographic microscope sensitive to linear diattenuation of biological samples using two linear polarizers. We validate our proposal by imaging calcium oxalate crystals and potato starch grains.
Low resolution initialization for rapid iterative convergence of 3D refractive-index
Authors: Haimowitz Max , Ziemczonok Michał , Krauze Wojciech , Kuś Arkadiusz , Chowdhury Shwetadwip
Published: December 2022

This paper introduces a novel approach to initialize an iterative 3D refractive-index reconstruction process. This approach requires no new data to be collected, and enables faster and more stable convergence of the iteration process.
Label-Free Monitoring of Perioperative Leukocyte Alternations After Cardiac Surgery Utilizing Digital Holographic Microscopy
Authors: Steike David Rene , Hessler Michael , Greve Burkhard , Kemper Björn
Published: December 2022

In a prospective observational pilot study, we evaluated label-free quantitative phase imaging (QPI) by digital holographic microscopy (DHM) as tool to describe perioperative changes in biophysical cell properties of lymphocytes and monocytes after cardiac surgery.
Lensless digital holographic microscopy with enhanced signal-to-noise ratio for live neural cell imaging
Authors: Trusiak Maciej , Rogalski Mikołaj , Arcab Piotr , Mirecki Bartosz , Rogujski Piotr , Stanaszek Luiza
Published: December 2022

Lensless digital holographic microscopy, upon numerical hologram reconstruction, provides large field-of-view amplitude and phase maps highlighting absorptive and refractive features of studied objects. Deploying constrained iterations we increase signal-to-noise-ratio of hologram reconstruction for live-cell imaging.
Suppressing the zero-frequency component of hologram with Hilbert-Huang transform in single-shot off-axis holography
Authors: Gan Chuli , Zhan Xiaojiang , Ding Yi , Xi Jiangtao
Published: December 2022

This paper proposes a method based on Hilbert-Huang transform to suppress the zero-frequency component of holograms with only one shot. It can effectively improve the quality of reconstructed phase objects.
Multi-depth Hologram Generation with Unsupervised-learning Based Computer-generated Holography
Authors: Shui Xinghua , Zheng Huadong
Published: December 2022

Unsupervised-learning based computer-generated holography provides an approach for 2D hologram generation. We propose an unsupervised learning network for multi-depth hologram generation with fully utilizing the different representations of multi-depth object.
Defect Detection of Fresco Samples using Digital Holography
Authors: Liu Yuhang , Zhou Wenjing , Zheng Huadong , Zhang Hongbo , Yu Yingjie
Published: December 2022

A novel portable digital holographic speckle pattern interferometer instrument was developed to detect scathes of fresco samples. Results show that the proposed technique achieves a high accuracy of 3D imaging of the sample.
Accurate Salient Object Detection and Segmented Point Cloud Gridding Methods for Real Objects based Full-Color Holographic System
Authors: Zhao Yu , Bu Jing-Wen , Zhu Li-Ming , Zhu Jin-Rong
Published: December 2022

We propose 3D salient object detection and segmented point cloud gridding methods to accelerate the real object-based full-color holographic system. The feasibility of the proposed methods is confirmed by experiments.
Deep learning based HiLo optical sectioning imaging
Authors: Chia Yu-Hsin , Vyas Sunil , Huang Yi-You , Luo Yuan
Published: December 2022

We present a deep learning based HiLo optical sectioning imaging method, which utilizes a U-net model to perform image to image transformation for HiLo imaging. Our method can reduce the image acquisition time by half.
Multi-Classification of Cell Lines using DHM and Machine Learning
Authors: Sun Anyu , Lam Van , Phan Thuc , Chang Lin-Ching , Nehmetallah George , Raub Christopher
Published: December 2022

We aim to achieve high performance classification of four cell lines, two breast cancer and two non-cancer, with varied epithelial and mesenchymal morphologies, and to determine the best machine learning model and to identify features most strongly influencing model performance.
A Comparison of the Resolution Obtained Using Two Regimes of Digital In-line Holographic Microscopy
Authors: Khorshad Ali Akbar , Devaney Nicholas
Published: December 2022

Digital In-line Holographic Microscopy (DIHM) provides 3D images at micron resolution, where setup simplicity is required. It has been shown that there are two operating regimes for DIHM, having high or low magnification. We show that the high-magnification DIHM provides better resolution and show the results of our setup for imaging 1µm particles.
Lensless magnified holographic projection based on an unsupervised neural network technology
Authors: Li Xingjian , Su Ping , Xia Bizhong
Published: December 2022

A new method is proposed to generate amplitude-only holograms in a lensless magnified projection system based on the unsupervised neural network technology. Simulation demonstrated that the method can generate high-quality holograms in 0.22s.
3D Refractive Index Estimation Based on Partially-Coherent Optical Diffraction Tomography (PC-ODT) and Deep Learning
Authors: Bazow B. S. , Phan T. , Raub C. B. , Nehmetallah G.
Published: December 2022

ODT has emerged as a powerful tool to obtain label-free 3D refractive index (RI) estimation of biological specimens. This work aims to improve 3D RI retrieval methods for PC-ODT using iterative and network based inverse solutions.
Method for Computer-Generated Hologram Compression with Attention Based Quantum Inspired Neural Network
Authors: Shen Zhelun , Yang Guanglin , Xie Haiyan
Published: December 2022

An attention-based quantum-inspired neural network is proposed to compress Computer-Generated Hologram, spatial attention mechanism is applied to capture long-range dependencies and enhance the feature representation ability of networks, and experiments show the superiority of our method.
Layer-based method for distortion correction of electron holographic 3D image display
Authors: Zhang Chao , Yang Guanglin , Xie Haiyan
Published: December 2022

A fast calculation method for distortion-free magnification of 3D image in electron holography using a conventional lens based on the optical reversibility theorem and layer-generated hologram is proposed. Experiment shows that this method is effective.
Adaptive optical focusing for Enhanced Underwater Wireless Optical Communication with Parametric Hologram Optimisation
Authors: Nie Jiewen , Tian Lei , Yue Song , Zhang Zichen , Yang Haining
Published: December 2022

A adaptive beam-shaping method is proposed for improving underwater wireless optical communication with two types of parametric holograms, leading to the tenfold amplification in underwater transmission efficiency of a 30m/100Mbps communication link.
Gaussian-packet assisted holography for single-shot spectroscopic imaging of cold atoms
Authors: Huang Xing , Zhao Jian , Wang Yuzhuo , Wu Saijun
Published: December 2022

Coherent forward emission from cold atoms illuminated by spherical waves can be modeled by Gaussian packets, facilitating holographic wavefront retrieval. Aided by the complex Gaussian-fits, we demonstrate spatially resolved atomic spectroscopy with interferometric accuracy.
Lensless Imaging with a Generalized Convolutional Framework
Authors: Ma Yuchen , Wu Jiachen , Cao Liangcai
Published: December 2022

A generalized explicit-restriction convolutional framework for lensless imaging is implemented by incorporating multiple hardware restrictions into the forward model. The proposed framework presents reconstructions with better perceptual quality and 4 × super-resolution.
Zero-shot learning for holographic context analysis in microplastics probing
Authors: Zhu Yanmin , Lo Hau Kwan Abby , Yeung Chok Hang , Lam Edmund Y.
Published: December 2022

A zero-shot learning method with attribute embedding is developed for holographic image analysis and microplastics probing. Experimental results show its efficacy in identifying the unknown microplastics and alleviating the need for manual dataset class annotation.
Hardware-in-the-loop Optimization for Hologram Rendering in Holographic Near-eye Display
Authors: Xia Xinxing , Yang Furong , Wang Weisen , Shui Xinghua , Guan Yunqing , Yu Yingjie
Published: December 2022

We propose a novel deep-learning-based hologram generation method with the end-to-end optimization with the combination of all optical devices. Experiments have been carried out to verify its feasibility.
Digital content generation for full-color holographic stereogram printing using a single phase-only SLM
Authors: Khuderchuluun Anar , Erdenebat Munkh-Uchral , Amgalan Tuvshinjargal , Kwon Ki-Chul , Gil Sang-Keun , Jeon Seok-Hee , Kim Nam
Published: December 2022

Digital content generation for full-color holographic stereogram printing using a single phase-only SLM is presented. The digital content data is generated within the fast IDP-based computation and computer-generated hologram (CGH) generation for phase-modulated full-color hogel.
Comparison of Lossy Compression Method for Object Light Data of Hologram
Authors: Sakamoto Yuji , Oi Hiroki
Published: December 2022

This article reports the results of comparing the compression of object light data for holograms using various lossy compression methods: JPEG, vector quantization (VQ), JPEG2000, and fractal compression. The efficiencies were JPEG2000 >fractal compression >VQ >JPEG at compression rates from 1% to 20%. In particular, when the PSNR was large, it became clear that the compression efficiency of JPEG2000 was very good.
Phase imaging for digital holography with deep learning
Authors: Xiong Chencen , Ren Zhenbo , Di Jianglei , Zhao Jianlin
Published: December 2022

Deep learning has been widely employed for digital holographic reconstruction. In this paper, we present a learning-based method for phase imaging from digital holograms without complicated and notorious operations such as phase unwrapping.
digHolo : High-speed library for off-axis digital holography and Hermite-Gaussian decomposition
Authors: Carpenter Joel
Published: December 2022

digHolo is an open-source library for reconstructing optical fields using off-axis digital holography. The library is particularly efficient at decomposing fields into Hermite-Gaussian coefficients and related bases.
Low-pass Filtering Phase Aberration Compensation for Digital Holographic Microscopy Using Complex Amplitude Extension
Authors: Shan Mingguang , Bi Yuming , Liu Lei , Zhong Zhi , Yu Lei
Published: December 2022

A low-pass filtering phase aberration compensation method using complex amplitude extension is proposed for digital holographic microscopy. Some experiments are conducted to verify the feasibility and validity of the proposed method.
Off-axis hologram simulation and reconstruction of particle in a pipe
Authors: Wang Lei , Wu Yingchun , Zhao Yue , Wu Xuecheng
Published: December 2022

The whole recording and reconstruction processes based on the ABCD transfer matrix of the digital off-axis holography through a pipe are researched. Comparisons of the simulations between inline and off-axis holography are presented.
Synchronous Gesture Interaction for Flat-Panel+Integral Imaging
Authors: Wei Jian , Guo Jiaqi , Guo Xiaoyuan , Jia Yong , Wang Qi , Wang Shigang
Published: December 2022

A method of gesture interaction for simultaneous flat-panel and integral imaging is proposed. It supports synchronously adjusting the viewpoint or scale of the 2D and naked-eye 3D images via viewer’s gestures, by exploiting the high efficiency of NVIDIA Optix in ray casting and Leap Motion in gesture recognition.
Adaptive optical quantitative phase imaging with annular illumination Fourier ptychographic microscopy
Authors: Zuo Chao , Shu Yefeng , Sun Jiasong
Published: December 2022

We propose an adaptive optical QPI method to solve time-varying aberrations in long-term imaging based on Fourier ptychographic microscopy. Only a few images captured under the annular matched illumination are required to realize the aberration-free live-cell observation.
Line-shaped laser lithography for efficient fabrication of large-area subwavelength nanogratings
Authors: Xu Kang , Huang Lingyu , Xu Shaolin
Published: December 2022

Subwavelength nanogratings for optical modulation have attracted significant attention for efficient large-area fabrication. We developed a far-field laser nanofabrication method, called line-shaped laser lithography, to ablate thin films with separated line-shaped ultrafast laser pulses on substrates into multiple nanogratings. The millimeter pulse length and high-speed scanning for a single-pulse ablation ensure exceptionally high large-area fabrication efficiency. Moreover, nanogratings with a sub-100 nm linewidth (e.g., a 57 nm linewidth (

∼

λ

/

9

) nanograting on 10 nm Au film) were generated based on the Marangoni effect. An ultra-uniform large-area (

6

×

15

m
m

2

) nanograting with a width of 132 nm and a length-to-width ratio of

∼

45

,

500

was achieved in only 1.5 s. In particular, diversified nanogratings can be obtained by designing scanning strategies, including moiré, blaze-like, Dammann, and 2D nanogratings, revealing light modulations in diffraction and beam splitting.
Long-term validation of a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the rapid detection of SARS-CoV-2 from March 2020 to October 2021 in Central Africa, Gabon
Authors: Abe Haruka , Ushijima Yuri , Bikangui Rodrigue , Ondo Georgelin Nguema , Moure Ayong , Yali-Assy-Oyamli Yoric , Yoshikawa Rokusuke , Lell Bertrand , Adegnika Ayola A. , Yasuda Jiro
Published: December 2022

Background

Despite the development of several methods for diagnosing COVID-19, long-term validation of such methods remains limited. In the early phase of the COVID-19 pandemic, we developed a rapid and sensitive diagnostic method based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) methodology, which is suitable for point-of-care application or for use in resource-limited settings to detect SARS-CoV-2. To assess the applicability of the RT-LAMP assay technique to resource-limited regions, such as rural areas in Africa, and to verify the usability of the method against various SARS-CoV-2 variants, the method was validated using clinical samples collected longitudinally during the pandemic.

Methodology/Principal findings

First, the sensitivity of the RT-LAMP assay for detecting 10 SARS-CoV-2 variants was evaluated using viral RNA samples extracted from cell culture with a portable battery-supported device, resulting in the successful detection of 20–50 copies of the viral genome within 15 min, regardless of the variant. COVID-19 positive samples collected in Gabon between March 2020 and October 2021 were used to evaluate the sensitivity of the assay and to calculate the copy number of the SARS-CoV-2 genome. More than 292 copies of the viral genome were detected with 100% probability within 15 min in almost all tests.

Conclusions

This long-term validation study clearly demonstrated the applicability of the RT-LAMP assay for the clinical diagnosis of COVID-19 in resource-limited settings of Africa, such as rural areas in Gabon. The results show the potential of the assay as a promising COVID-19 diagnostic method, especially in rural and remote regions located far from the official diagnosis facilities in urban or semi-urban areas.
Acute effect of blueberry intake on vascular function in older subjects: Study protocol for a randomized, controlled, crossover trial
Authors: Del Bo’ Cristian , Tucci Massimiliano , Martini Daniela , Marino Mirko , Bertoli Simona , Battezzati Alberto , Porrini Marisa , Riso Patrizia
Published: December 2022

Aging is associated with an increased risk of developing cardiovascular disease which is often accompanied by a decline in vascular health and function. Current evidence suggests that berries may have a potential role in the modulation of vascular function, but dietary interventions are still needed to confirm findings, especially in older subjects. In the context of the MIND FoodS HUB project, this study aims to investigate the effect of a single serving of blueberry (250 g of blueberry versus a control product) in a group of older subjects (≥ 60y) through a randomized, controlled, cross-over dietary intervention trial. Specifically, the study evaluates the absorption kinetics of bioactives following the blueberries intake and the effects on markers related to oxidative stress, inflammation, and vascular function analyzed at different time points. By considering a drop-out rate estimate of 25%, at least 20 subjects will be recruited in the study. The study will provide evidence to support the potential beneficial effects of blueberry and its bioactive compounds on vascular function in a group of population more susceptible to vascular dysfunction and to the development of cardiovascular diseases. Moreover, the study will contribute the analysis of several metabolic and functional markers that can support the biological plausibility of the results obtained. Finally, the trial will provide data on the absorption and metabolism of blueberry bioactives which will be used to study their association with the different markers under study.

Trail registration: The trial is registered at ISRCTN (http://isrctn.com/ISRCTN18262533); May 7, 2021.