bluuebunny/crossref_metadata_2025 huggingface dataset:
The Potential Revolution of the Free Electron Laser for UV Resonance Raman Spectroscopy in Biological, Structural and Dynamical Studies
Authors: Asher Sanford A.
Published: September 2022

Advances in laser light sources have been the major driving force for progress in the development and application of Raman spectroscopy. The advances have utilized both the increased tunability of the laser sources as well as their short pulse lengths and high peak powers to both increase the information content as well as give dynamical information. We will discuss the revolution in the understanding of molecular and biomolecular structure which will derive from the application of FEL laser sources. We can easily extrapolate the utility of these new sources from our recent extensive UV Raman measurements using state-of-the-art commercial laser sources and non-linear optical conver sion techniques.
Ultrahigh-Speed Measurement of Supersonic Combustion with a UV Free-Electron Laser
Authors: Pitz Robert W.
Published: September 2022

In subsonic turbulent combustion, laser techniques such as laser velocimetry, laser-induced fluorescence (LIF), Raman scattering, and Mie scattering have been applied extensively. Point measurements using these techniques have given time and spatially resolved measurements of temperature, species concentration, mixture fraction, and velocity. UV Raman scattering probes using the KrF excimer laser are being developed for measurement of supersonic flows. In addition, two-dimensional (2D) imaging has been developed using LIF and Raman scattering to detect flow field properties. These techniques can be readily applied in supersonic flows to obtain statistical information on the supersonic combustion.
The Radiobiology of Ultrasoft X-rays
Authors: Freyer James , Schillaci Mario , Carpenter Susan , Cornforth Michael , Sebring Robert , Schor Patricia , Wilder Mark , Thompson Kathryn , Raju Mudundi
Published: September 2022

We have an ongoing project using ultrasoft x-rays as a tool to investigate the mechanisms of radiation-induced damage in biological systems. The data which are derived from these studies are used to test the assumptions of current models of the biological and chemical mechanisms of radiation damage. In principle, refinement of these models should aid in the extrapolation of biological data obtained at high radiation doses to the low-dose region. Basic mechanistic data may also improve our understanding of the therapeutic application of radiation in the treatment of cancer. Soft x-rays are particularly attractive for these studies because they deposit their energy over nanometer-scale dimensions, comparable to the size of critical target structures within mammalian cells. For example, 0.28 keV characteristic x-rays from carbon generate photoelectrons which deposit all of their energy over a range of 7 nm, comparable to the dimensions of DNA strands (2-3 nm) and DNA-histone complexes (10 nm). Thus, these radiations serve as very precise probes of the energy deposition and lesion interaction requirements for biological damage.
Photoionization and Photofragmentation Studies of Van Der Waals Complexes Using VUV Radiation
Authors: Walters E. A. , Grover J. R.
Published: September 2022

Van der Waals complexes are loosely bound clusters of atoms or molecules which can be made conveniently by free jet expansions of pure or mixed vapors through a supersonic nozzle. Although these complexes are bound only by 0-0.2 eV, they have unique geometries that can be determined by techniques such as microwave spectroscopy (1). These species are of considerable interest not simply from the perspectives of molecular structure and thermodynamics, but more so because they are, for chemically reactive pairs, frozen collision complexes which can be isolated long enough to permit inspection of features such as stepwise solvent effects, energy transfer in oriented reactants, induction of chemical reactions, preparation of cationic reaction intermediates, and nonstatistical effects in unimolecular decomposition of ionic complexes.
Molecular Photoionization and Photofragmentation Studies Using VUV Radiation
Authors: Sander Robert K. , Tiee Joe J.
Published: September 2022

It has long been recognized that studies of molecular processes such as photoionization and photofragmentation can provide valuable spectroscopic and chemical dynamics information that can lead to a detailed mechanistic understanding of the energetics, structure, and reactivity of molecular species. With the availability of high power and tunable lasers in the uv and visible region, substantial progress has been made in recent years in understanding molecular dynamics through photoionization and photofragmentation studies. These works, however, are limited to only a few selected molecules and in some cases involve multiple photon excitation. This is because most molecules undergo these molecular processes at excitation wavelengths shorter than 200 nm (i.e., in the VUV region) where few good laser sources are available. Synchrotron light sources have been applied to similar investigations in the VUV with limited success. The main difficulty appears to be the lack of spectral brightness of synchrotrons, particularly in state-specific photoexcitation studies where both high photon intensity and spectral resolution are essential.
Challenges in the Design and Fabrication of XUV Projection Lithographic Optics
Authors: Zernike F. , Wu F. Y.
Published: September 2022

In the last fifteen years, the density of integrated circuits has increased at a steady rate. The lithography needed to do this has mainly relied on the development of optical systems with increasingly larger numerical apertures (N.A.) rather than on a reduction of wavelength. However, at the presently used wavelengths, this method of increasing the N.A. cannot be extended beyond critical dimensions (C.D.) of about 0.7 μm. Consequently, if the trend towards higher density is to continue, microlithography systems using shorter wavelengths will be needed. Indeed, work is now being done using the mercury I line (365 nm) and with excimer lasers at even shorter wavelengths (248 nm and 193 nm) as sources. These sources could allow lithography with C.D.'s somewhat below 0.5 μm.
FEL Applications in Laser Etching and Ablation
Authors: Estler R. C. , Nogar N. S.
Published: September 2022

Much attention has been given recently to the laser etching and photoablation of insulating and polymeric films because of applications to the etching processes involved in the microelectronics industry. Interesting results have been noted for the wavelength dependence of the etching process in both polymeric1 and ceramic2 systems.
High Resolution Photoelectron Spectroscopy: Emphasis on Actinides
Authors: Arko A. J.
Published: September 2022

Photoelectron Spectroscopy (PES) covers a very broad range of measurements, disciplines, and interests. The present emphasis will be on actinide materials but the same arguments can apply to any part of the periodic table and indeed to other disciplines such as surface, atomic, and molecular studies. Almost the entire spectrum of PES measurements will benefit greatly from the development of the XUV-FEL. As the next generation light source, the FEL will result in improvements over the undulator that are larger than the undulater improvements over bending magnets. The combination of high flux and high inherent resolution will result in several orders of magnitude gain in signal to noise over measurements using synchrotron-based undulators. The latter still require monochromators. Their resolution is invariably strongly energy-dependent so that in the regions of interest for many experiments (hν > 100 eV) they will not have a resolving power much over 1000. In order to study some of the interesting phenomena in actinides (heavy fermions e.g.) one would need resolving powers of 104 to 105. These values are only reachable with the FEL.
Novel Magnetic Materials Research Using Free Electron Lasers
Authors: Bader S. D.
Published: September 2022

Synchrotron-radiation sources have dramatically increased the research capabilities of materials scientists. This increase has motivated advances in source development, from the (i) early, "parasitic" stage, to the (ii) present-day, dedicated bending-magnet stage, to the (iii) proposed, all-insertion-device stage.
Telemetry and AI-based security P4 applications for optical networks [Invited]
Authors: Cugini Filippo , Scano Davide , Giorgetti Alessio , Sgambelluri Andrea , De Marinis Lorenzo , Castoldi Piero , Paolucci Francesco
Published: September 2022

This paper presents the potentials and challenges of programmable packet-optical nodes encompassing coherent pluggable modules applied in the context of optical metro networks. Two innovative applications of P4-based data plane programmability are then presented. The first targets the monitoring and processing of optical telemetry data/metadata directly in the forwarding plane. The second one focuses on the deployment of deep neural networks in P4 chipsets, effectively supporting in-network distributed cyber security functionalities in packet-optical nodes.
Optoelectronic-VLSI for Switched Data Networking
Authors: Krishnamoorthy A. V. , Ford J. E.
Published: September 2022

It is becoming evident that the switched-networking of multiple general-purpose processors is an efficient and cost-effective path to achieving high-performance computing engines. In such distributed computing environments, the interconnection network typically represents a fundamental performance bottleneck, as electrical interconnect technologies struggle to keep pace with increasing demand for more connectivity, throughput, and rapidly diminishing processor clock-cycle times. The demands made on the data network include (i) high throughput communication, (ii) low contention and (iii) simple physical-layer communication protocols. Additional features of low latency data transport and packet switched operation are desirable.
Optical Interconnect Solutions to the I/O-Problem in Future CMOS Generations
Authors: Baets R.
Published: September 2022

Optical interconnect may offer a solution to the I/O problem in future CMOS systems but a major effort will be needed on integration—hybrid or monolithic—of efficient and compact transmitters and receivers as well as on alignment tolerant optical pathways. In this paper work is presented on the concerted efforts towards this goal in the EC-ESPRIT programme.
A Generalized Method for Tolerancing Polarization Losses in Free-Space Optical Interconnections
Authors: Ayliffe M. H. , Plant D. V.
Published: September 2022

As research in the field of free-space optical interconnects (FSOI) evolves, better simulation methodologies are required to facilitate the design process and provide useful and accurate system modeling. Simulation methods addressing these issues have already been proposed [1, 2]. By modeling the power flow of light beams as they propagate through an interconnect, these methodologies provided system performance information in terms of signal-to-noise ratio, bit-error rate and bandwidth.
Optical Transpose Interconnection System for Vertical Emitters
Authors: Blume Matthias , Marsderi Gary C. , Marchand Philippe J. , Esener Sadik C.
Published: September 2022

Optical interconnections have advantages over electrical interconnections in terms of speed, power, and density for high-speed links over distances on the order of centimeters1. In this paper, we are concerned with a particular interconnection pattern, the k-shuffle2. The optical transpose interconnection system3 (OTIS) architecture provides this pattern using only a pair of lenslet arrays. Here, we describe a novel optical system design for implementing the OTIS architecture utilizing vertical emitters (OTIS-VE). In contrast, for high efficiency and power uniformity, earlier designs required individually directed transmitters. We carry out a Gaussian beam analysis to optimize the system parameters and to show that fabrication of the system is feasible.
Optical Switching at Telecom Wavelengths Using Double Phase Conjugate Mirror in InP: Fe
Authors: Wolffer N. , Gravey P. , Del Burgos S.
Published: September 2022

The Double Phase Conjugate Mirror (DPCM) [1] is particularly attractive for the realisation of free space bi-directional optical links, owing to the self aligning properties of phase conjugation[2].
ATM distribution network using an optoelectronic VLSI switching chip
Authors: Lentine A. L. , Reiley D. J. , Novotny R. A. , Morrison R. L. , Sasian J. M. , Beckman M. G. , Buchholz D. B. , Hinterlong S. J. , Cloonan T. J. , Richards G. W. , McCormick F. B.
Published: September 2022

We describe an optoelectronic switching system demonstration that implements part of the distribution fabric for a large ATM switch. The system uses a single optoelectronic VLSI modulator-based switching chip with more than 4000 optical I/O. The optical system images the input fibers from a two dimensional fiber bundle onto this chip. The optomechanical design allows the system to be mounted in a standard electronic equipment frame. A large section of the switch was operated as a 208 Mb/s time multiplexed space switch, which can serve as part of an ATM switch using the appropriate out-of-band controller. A larger section with 896 input light beams and 256 output beams was operated at 160 Mb/s as a slowly reconfigurable space switch. In this presentation, we will give an overview of the demonstration system, including the motivation, architecture, switching chip, optical system, input lasers, fiber bundle array, opto-mechanics, control software, and experimental results.
Design and Construction of Experimental Optical Array Logic Network Computing System
Authors: Tanida Jun , Awatsuji Yasuhiro , Sakamoto Nobuyuki , Ichioka Yoshiki
Published: September 2022

Optical interconnection is considered as one of promising techniques for high-performance information processing. Maturity of very large scale integration and optoelectronic device technologies promotes realization of the practical systems. Although such systems apply light wave just for information carrier, we should recognize and confirm potential capabilities of light for parallel computation. Following this consideration, the authors have presented an architecture of optical array logic network computing (OAL-NC) [1]. In the OAL-NC, a concept of optical compunection, or merge of optical interconnection and computation, is emphasized. Through experimental demonstration, we are going to clarify potential capabilities of the OAL-NC architecture.
Point to point interconnections using an entirely diffractive optical system
Authors: Morrison Rick L. , Buchholz D. Bruce
Published: September 2022

Anticipation of large scale integration of vertical cavity surface emitting laser (VCSEL) and receiver arrays with CMOS processing circuits is driving the investigation of optical interconnects to find a strategy suitable to deliver this high throughput technology and yet acceptable to conventional electronics system designers who are unfamiliar and perhaps uncomfortable with conventional optics. A short list of desirable system attributes would include: densely packed optical channels, inexpensive and compact packaging, and optomechanical systems without critical micron level alignment tolerances.
Analysis of GRIN Rod and Conventional Optical Systems for Imaging of Two-Dimensional Optoelectronic Device Arrays
Authors: McArdle Neil , Ishikawa Masatoshi
Published: September 2022

Recent developments in the design and fabrication of large two-dimensional arrays of optoelectronic devices for parallel optical processing and interconnections has impacted the need for high performance and cost effective optical imaging systems.
Efficient Optical Sensor Design For Multi-Function Integrated Emitter-Detector Arrays
Authors: Babbitt Wm. Randall , Darling Robert B.
Published: September 2022

Smart pixels, the integration of photodetector arrays and processing electronics on a single semiconductor chip, have been driven by its capability to perform parallel processing of large pixelated images and in real-time reduce a complex image into a manageable stream of signals that can be brought off-chip.1-2 In recent years, optical modulators and emitters have been integrated with photodetectors and on-chip electronics.3-5 The driving applications for this have been highly parallel optical interconnects and optical switching networks.
A Neural Switch Controller
Authors: Webb Rod
Published: September 2022

In a system with many variables, finding their optimum values is, in general, a computationally intensive process that scales badly with the number of variables. The potential benefit of accelerating the solution of such problems with optical computing techniques is therefore large. Considerable success has been reported [1] with the use of Hopfield neural networks for optimisation and neural network architectures lend themselves to parallel operation in hardware. Optics is appropriate for implementing the large number of connections required, which it can provide very efficiently when there is any regularity in the interconnect pattern.
Broadband and Efficient Adaptive Method for True-Time-Delay Array Processing
Authors: Wagner K. H. , Kraut S. , Griffiths L. , Weaver S. , Weverka R. T. , Sarto A. W.
Published: September 2022

We present a novel approach to the optical implementation of true-time-delay (TTD) beamforming for large adaptive phased arrays. Our new algorithm, BEAMTAP (Broadband and Efficient Adaptive Method for TTD Array Processing), decreases the number of tapped delay lines (TDLs) required to process an N-element phased array antenna from N to only 2.1 This new adaptive system still provides the full NM degrees of freedom of a conventional N-element time delay beamformer with M taps each, enabling it to fully and optimally adapt to an arbitrarily complex spatio-temporal signal environment containing broadband signals, narrowband and broadband jammers, and noise, all of which can arrive from arbitrary angles. In comparison with conventional time-domain beamformers, this algorithm is readily implemented optically since the elimination of the delay lines between weights allows photorefractive crystals (PRC) to be used to implement the huge numbers of adaptive weights as required for large arrays while still using only 2 TDLs.
Optical Implementation of the stream cipher based on one dimensional Cellular Automata
Authors: Madjarova M. , Kakuta M. , Yamaguchi M. , Ohyama N.
Published: September 2022

Rapid expansion of computer networks in all aspects of today’s society brings undeniable benefits but also serious security problems. Cryptography is one of the tools which ensures security, integrity and authentication of electronic data. Ever increasing standards for data security urge introducing new, complicated algorithms, or increasing of the key length, which require more computing power and time. Together with the increasing amount of data to be protected this may turn into system bottleneck. To avoid this, new algorithms and architectures are being extensively researched. Optical computing systems may offer valuable alternative with the inherent parallelism and high interconnectivity, allowing encryption of large block of data in parallel using very long key. In this way variety of biometrical data such as fingerprint, retinal or facial images can be used as a key, instead of a short password. This will lead to increase of the security not compromising the speed at the same time. One of the most promising optical architecture is the cellular. A number of optical cellular architectures have been proposed mainly for image processing [3-10]. A promising new application field can be cryptography and random pattern generation. As first attempt in this direction we propose optical implementation of CA rule
a
i
'=ai−1XOR(a
i
ORai+1) based Stream Cipher, suggested by S. Wolfram [1].
Optimization of Optoelectronic Cellular Interconnections
Authors: Hoanca Bogdan , Sawchuk A. A.
Published: September 2022

The binary optoelectronic cellular hypercube (CH) [1] was proposed to improve the interconnection performance of mesh-connected arrays of processors. A mesh-reduced CH (M-RCH) [2], combining the mesh for short distance connections and a reduced set of the CH interconnects, was shown to outperform the CH, by reducing the number of clock cycles per data shift. We present in this paper a generalized optimal cellular interconnection (OCI), which simultaneously minimizes the optical fan out and the number of clock cycles per data shift. Our design optimizes the allocation of the optical link distances, minimizes the optical fan-out (for efficiency and ease of design of the optical interconnect), makes use of the electronic mesh where it is more efficient than the optical interconnect, and shows atheoretically proven minimum latency.
One-Dimensional Input Parallel Optoelectronic Correlator Chip
Authors: Yayla Gökçe , Kibar Osman , Marchand Philippe J.
Published: September 2022

In some high-performance parallel optical access memory disks being developed, the data is retrieved as a linear array. When interfacing the disk readout system to a VLSI chip that contains the required detectors and their associated circuits, it eases the design of the custom VLSI chip. This is because the constraint of having to layout the circuitry as a 2-D matrix is removed, thus the silicon is more efficiently used and design automation tools can be used more effectively. Use of a differential detect on scheme is also easier in the 1-dimensional case.
Storage Limits of Two-Photon Based Three-Dimensional Memories
Authors: Urey Hakan , McCormick Frederick B.
Published: September 2022

Two-photon absorption 3-D optical memories have the potential for simple media fabrication, parallel access for high data transfer rates, high volumetric storage density, and low raw bit error rates (BER).1-2 The writing or erasure takes place at the intersection of two orthogonally propagating beams where a unique physical location is allocated to each stored bit. The data can be stored and retrieved in several formats in a single operation. By using either orthogonal-propagating beams or counter-propagating beams, it is possible to control the region of overlap of the two beams to be a single point, a line, or a plane. We will refer to those data formats as bit, vector, and image (or page) storage.
Packaging Optoelectronic/VLSI Chip Using Polarization Selective Computer Generated Holograms
Authors: Xu Fang , Ford Joseph E. , Krishnamoorthy Ashok V. , Fainman Yeshayahu
Published: September 2022

Integration of microlenses with III-V devices such as lasers and detectors has been previously demonstrated1,2,. Integration of the optics directly with the optoelectronic (OE) devices allows compact and reliable packaging for optical interconnect applications. The optical signals are routed to photodetectors and transmitted from the modulators or laser devices using arrays of diffractive optical elements (DOEs) or micro-optics components3. In general, these optical input and output signal paths need to be different, which, in turn, implies that the corresponding DOE or micro-optics arrays must be capable of providing dual functionality in implementing the communication links to and from the VLSI array with optical I/Os. However, since the conventional DOE or micro-optics components do not possess this dual functionality, additional components such as polarization beam splitters are required to separate the input and the output signals4. In this paper, we present the first integration of beam-forming computer generated holograms (CGH) with optoelectronic (I/O) devices flip-chip bonded to CMOS VLSI electronics, and the first integration of a polarization-selective CGH with an optoelectronic device.
Separated nano jetting and micro jetting regimes by double-pulse irradiation of a metal film: towards multiscale printing
Authors: Murali Anjali , Li Qingfeng , Grojo David , Alloncle Patricia , Delaporte Philippe
Published: September 2022

The Double-Pulse (DP) version of the Laser-Induced Forward Transfer (LIFT) technique holds great potential to improve the resolution and flexibility of printing applications. In this study, we investigate the transfer of copper. A long laser pulse is first applied to melt thin copper films deposited on a transparent substrate, followed by an ultrashort laser pulse to initiate the transfer of the liquid material towards a receiver substrate. Time-resolved imaging experiments reveal that ejections from nanodrops to liquid jets with controllable diameters, from few micrometers down to the nanometers scale can be obtained with the control parameters of DP-LIFT. Comparing simulation and experiments we discuss how the ejection characteristics are governed by various factors including the shape, diameter and temperature of the melted pool created with the first long pulse. While the formation of microjets is due to the dynamical deformation of the melted film, as for the conventional LIFT process applied with liquid donors, the results indicate a different and distinct process for the formation of nanojets. We extrapolate from the observations a feature caused by the interaction of the shockwave, generated by the femtosecond laser irradiation, with the deformed surface of the pool. Ultimately, we establish the range of irradiation parameters leading to the observation of single separated microjets and nanojets. The latter are accompanied by nano printing demonstrations. Considering all accessible regimes together, a unique technological perspective is the possibility to achieve multi-scale printing from the same donor.
Indoor optical fiber eavesdropping approach and its avoidance
Authors: Hao Haiqing , Pang Zhongwang , Wang Guan , Wang Bo
Published: September 2022

The optical fiber network has become a worldwide infrastructure. In addition to the basic functions in telecommunication, its sensing ability has attracted more and more attention. In this paper, we discuss the risk of household fiber being used for eavesdropping and demonstrate its performance in the lab. Using a 3-meter tail fiber in front of the household optical modem, voices of normal human speech can be eavesdropped by a laser interferometer and recovered 1.1 km away. The detection distance limit and system noise are analyzed quantitatively. We also give some practical ways to prevent eavesdropping through household fiber.
Multi-material spectral photon-counting micro-CT with minimum residual decomposition and self-supervised deep denoising
Authors: Di Trapani V. , Brombal L. , Brun F.
Published: September 2022

Spectral micro-CT imaging with direct-detection energy discriminating photon counting detectors having small pixel size (< 100×100 µm2) is mainly hampered by: i) the limited energy resolution of the imaging device due to charge sharing effects and ii) the unavoidable noise amplification in the images resulting from basis material decomposition. In this work, we present a cone-beam micro-CT setup that includes a CdTe photon counting detector implementing a charge summing hardware solution to correct for the charge-sharing issue and an innovative image processing pipeline based on accurate modeling of the spectral response of the imaging system, an improved basis material decomposition (BMD) algorithm named minimum-residual BMD (MR-BMD), and self-supervised deep convolutional denoising. Experimental tomographic projections having a pixel size of 45×45 µm2 of a plastinated mouse sample including I, Ba, and Gd small cuvettes were acquired. Results demonstrate the capability of the combined hardware and software tools to sharply discriminate even between materials having their K-Edge separated by a few keV, such as e.g., I and Ba. By evaluating the quality of the reconstructed decomposed images (water, bone, I, Ba, and Gd), the quantitative performances of the spectral system are here assessed and discussed.
Effects of the cone angle on the SERS detection sensitivity of tapered fiber probes
Authors: Qin Yanyan , Huang Ruidong , Lu Fengya , Tang Haibin , Yao Bo , Mao Qinghe
Published: September 2022

In this paper, we investigate the effects of taper angle on the SERS detection sensitivity using tapered fiber probes with single-layer uniform gold spherical nanoparticles (GSNs). We show that the photothermal damage caused by excessive excitation laser power is the main factor that restricts the improvement of detection sensitivity of tapered fiber probes. Only when the cone angle is appropriate can a balance be achieved between increasing the excitation laser power and suppression of the transmission and scattering losses of the nanoparticles on the tapered fiber surface, thereby obtaining the best SERS detection sensitivity. Furthermore, the optimal cone angle depends on the complex refractive index of the equivalent composite dielectric (ECD) layer containing GSNs. For three SERS fiber probes with different ECD layers, the optimal cone angles measured are between 11-13°.
Orthogonal separation of arbitrary vector beams from non-polarized light waves based on a patterned liquid-crystal photo-alignment
Authors: Chen Mingce , Ye Mao , Wang Zhe , Liu Taige , Hu Chai , Liu Kewei , Shi Jiashuo , Zhang Xinyu
Published: September 2022

An effective method for orthogonally separating arbitrary vector polarized beams from non-polarized incident light waves is proposed in this Letter. A tunable patterned spatial distribution of liquid-crystal (LC) molecules can be effectively constructed based on both the initial photo-alignment and the electrically controlled birefringence of nematic LC materials. The LC photo-alignment over a smooth surface without any common nano-grooves leads to a highly efficient light-wave transformation by inducing a desired initial arrangement of LC directors and then acquiring extraordinary light waves with the needed, or even arbitrary, spatial polarization. The vector polarized beams can be highly converged according to a microhole-patterned electrode and a gradient refractive index distribution of the LC layer, which is driven and adjusted by an applied signal voltage. Due to the intrinsic polarization sensitivity of nematic LC materials, the formed gradient refractive index appearance only corresponds to extraordinary light waves. The proposed approach provides a way to achieve the orthogonal separation of arbitrary vector beams from non-polarized light waves. Moreover, it can be further utilized to generate and obtain arbitrary vector beams, as well as to perform adaptive light-beam convergence or even the focusing of arbitrary vector beams, which is expected to advance the development of vector beam generation and manipulation, thereby stimulating potential applications.
N-band photonic Hopf insulators based on 2D microring lattices
Authors: Leng Bo , Van Vien
Published: September 2022

Hopf insulators are topological insulators whose topological behavior arises from the nontrivial mapping from a 3D sphere to a 2D sphere, known as the Hopf map. The Hopf map, typically encountered in the study of spinor and Skyrmion systems, is classified topologically by an integer invariant called the Hopf index. Here we show that, owing to the periodic circulation of light inside each microring, a 2D lattice of microring resonators can emulate an N-band photonic Hopf insulator with nontrivial Hopf index. In particular, we show by numerical computation and direct analytical proof that the N-band Hopf index of the microring lattice is identical to its winding number. The result shows that the Hopf index is an alternative topological invariant for classifying 2D microring photonic lattices and establishes a correspondence between the Hopf insulator phase and the anomalous Floquet insulator phase of the lattice. More generally, our work shows that 2D microring lattices can provide a versatile nanophotonic platform for studying non-Abelian topological photonic systems.
Spectral sensor of the ethanol concentration in water based on photodiode optoelectronic chromatic dispersion
Authors: Liokumovitch Egor , Glasser Ziv , Sternklar Shmuel
Published: September 2022

Optoelectronic chromatic dispersion (OED) of a PN-type germanium photodiode is used for spectral sensing of ethanol concentration in water. A concentration sensitivity of 70 ppm is achieved. Spectral sensors based on OED in PN-type photodiodes can serve as low-cost on-chip devices for optical spectroscopy.
Multiple-Quantum-Well Binary-Phase Modulators for Optical Interconnections: Effects of Dead Zones
Authors: Inbar Hanni , Taghizadeh Mohammad R.
Published: September 2022

We investigate the effects of inactive regions (dead zones) in a multiple-quantum-well binary phase modulator used for free-space dynamic optical-interconnection applications.
Direct Bonding of InP to Si for Optoelectronic Integration
Authors: Wada Hiroshi , Kamijoh Takeshi
Published: September 2022

Integration of III-V optical devices on Si is an essential technology to realize optoelectronic integrated circuits (OEICs). Especially, fabrication of InGaAsP/InP long-wavelength lasers on Si is very attractive for optical interconnections between Si LSI chips because Si is transparent at the lasing wavelength.
Integrated VCSELs, MSM Photodetectors, and GaAs MESFETs for Low Cost Optical Interconnects
Authors: Liu Yue , Hibbs-Brenner Mary , Morgan Bob , Nohava Jim , Walterson Bob , Marta Terry , Bounnak Sommy , Kalweit Edith , Lehman John , Carlson Doug , Wilson Peg
Published: September 2022

Vertical Cavity Surface Emitting Lasers (VCSELs) and Metal-Semiconductor-Metal (MSM) photodetectors are two key components for high speed optical data communication and optical interconnect modules. In this paper we report a successful integration of VCSELs and MSM photodetectors and GaAs MESFETs on semi-insulating (S.I.) substrate.
Self Aligned Epitaxial Liftoff for Smart Pixels
Authors: Chang W. , Yablonovitch E. , Hansen M. , Fan C. , Esener S.C. , Efron U.
Published: September 2022

The need for increased processing speed in advanced computing systems is straining the limits of purely electronic systems. Opto-electronic systems may represent the future form of implementation of high throughput data processing systems. The components that are selected for Opto-Electronic data processing systems have to meet the requirements of both high speed and low power dissipation. GaAs/AlGaAs Multiple Quantum Well (MQW) Spatial Light Modulators (SLM) exhibit low switching power and very high speed. Moreover, they operate at voltages which are compatible with Si VLSI technology1. These make them attractive in high density optical information processing systems such as optical correlators. Thin film integration between Si integrated circuits and MQW modulators can be done by Epitaxial Lift-Off (ELO) technique. A major advantage of ELO is that Si circuitry and GaAs MQW modulators can be optimized individually and then integrated together resulting in improved yield and performance.
Demultiplexing 2.48 Gb/s Optical Signals with a Lower-Speed Clocked-Sense-Amplifier-Based Hybrid CMOS/MQW Receiver Array
Authors: Woodward T. K. , Lentine A. L. , Goossen K. W. , Walker J. A. , Tseng B. T. , Hui S. P. , Lothian J. , Leibenguth R. E.
Published: September 2022

The optoelectronic multiplexing and demultiplexing of data is a common operation on optical communication links, and one that is becoming more important as these links become increasingly prevalent. These operations permit multiple electronic data streams to be combined onto and removed from a single optical link, taking advantage of the high link-bandwidth available. Demultiplexing places particularly stringent demands on optoelectronic components. In this paper, we describe a method for demultiplexing optical data that utilizes clocked-optical receivers. This method permits the extraction of signals without the need for optoelectronic circuits operating at the full multiplexed-data rate, provided synchronization and timing information are available.
A new high resolution FLC/VLSI Spatial Light Modulator - First Impressions
Authors: Rankin I.D. , Burns D.C. , O’Hara A. , Underwood I. , Stevenson J.T.M. , Bodammer G. , Vass D.G. , Worboys M.R.
Published: September 2022

We have designed and constructed a small number of prototype spatial light modulators (SLMs) based on a pixel array of 512 x512. The digital CMOS backplane allows fast writing of binary data onto the FLC layer for optical readout. We anticipate the use of the design in coherent applications such as optical correlators and programmable holograms as well as incoherent applications such as miniature displays.
Continuing Development of an Infrared Optically Addressed Spatial Light Modulator
Authors: Eliasson Blake , Moddel Garret
Published: September 2022

The applications for spatial light modulators with sensitivity in the infrared spectrum include atmospheric compensation for imaging via phase conjugation [1], reconfigurable optical fiber interconnects and incorporation in search and track devices. The design goals for our device include: high frame rate (~ 1 kHz), sensitivity at 1.55 μm, and a high resolution (MTF = 50% at 40 lp/mm). Meeting these design specifications has resulted in many technical challenges.
Compensated Imaging by Real-Time Holography with Optically Addressed Spatial Light Modulators
Authors: Gruneisen Mark T. , Wilkes James M.
Published: September 2022

High- resolution imaging requirements push telescope designs to increasingly large apertures and consequently large primary mirror sizes. Conventional astronomical telescopes require high-optical-quality primary mirrors. In order to achieve and maintain high surface quality at large apertures, such mirrors are monolithic, extremely heavy and very costly to fabricate and transport. These considerations limit the aperture sizes of present day ground-based and space-based astronomical telescopes. In recent years, compensated imaging techniques have been studied as possible solutions to the problem of imaging with low-optical-quality primary mirrors. With relaxed requirements on the surface quality of the primary mirror, alternative lightweight architectures for telescope systems become feasible.
Image Processing and Optical Storage in a Resonator with an OASLM
Authors: Rehn H. , Kowarschik R.
Published: September 2022

Optically addressable spatial light modulators (OASLM's) are not only of use for the introduction of an incoherent intensity distribution to a coherent optical system, but also to realize optical image processing and storage if the same coherent beam is used to write and to read out the OASLM. In our contribution we report investigations on several optical systems, where the information that was read out coherently from a OASLM is processed by an optical system and then fed back to the rear side of the OASLM. Similar systems have been described in the literature for example to compensate wavefront aberrations in adaptive optics [1], or as a Fabry-Perot type OASLM with internal feedback [2]. We want to demonstrate the image processing and storage capabilities of such systems and will show how both amplitude and phase of a beam can be used for the processing.
High Diffraction Efficiency in Nematic Liquid Crystal Gratings For 1.5μm Optical Interconnects
Authors: Wolffer N , Coquillé R. , Vinouze B. , Gravey P. , Pain F. , Lorand P.Y.
Published: September 2022

Liquid crystals are frequently used as active holographic elements for beam deflection applications. Thanks to their small response time, ferroelectric liquid crystals are mostly studied for telecom applications. However, for routing applications, the reconfiguration rate is not a key parameter, on the other hand, nematic liquid crystals make it possible to produce phase ramps and therefore high efficiencies. [1 2 3 4 5 6-7]
Self-Tuned Fabry Perot Light Modulator Array
Authors: Harvey Phil , Esener Sadik
Published: September 2022

We are developing a surface-normal light modulator structure that has the potential to achieve low voltage (<5V) and high frequency operation (>few hundred MHz) operation with good contrast ratio (>20:1) and spatially uniform response over a large area (~1”x1”). The technique is based upon Fabry-Perot structures using electro-optic phase modulation materials. Conventional modulators of this type are well known for their sensitivity to optical path differences (resulting from, e.g., cavity thickness variations, cavity index variations, or uncollimated optical beams). Our approach is to replace the input mirror with an in-situ recorded holographic mirror, resulting in what we call a Self-Tuned Fabry Perot (STFP) modulator. We have previously demonstrated the STFP concept with a large (2.5mm x 2.5mm) single element modulator and collimated light. Here we present out latest experimental results of a 9x9 modulator array which uses a focusing lenslet array.
Photorefractive Materials for Lightwave Manipulation
Authors: WADA TATSUO , SASABE HIROYUKI
Published: September 2022

Photorefractive materials are the key materials in future lightwave manipulation systems based on real-time holography. Typical photorefractive materials are ferroelectric crystals, such as BaTiO3 and KNbO3. These crystalline materials have a unique set of principal axes, and must be used in bulk form. Therefore they require very careful growth and processing before they can be used. For this reason there has been excitement by the recent development of new organic materials which can be easily made into thin films, and after poling exhibit photorefractive properties.
Electrooptical spatial light arrayed modulator for free-space and waveguide optical data processing
Authors: Parfenov A. , Harada K. , Itoh M. , Yatagai T. , Tamaoki N.
Published: September 2022

Electro-optical polymers obtain very attractive features - such as large electro-optical coefficient, possibility to make waveguides, photoconductivity and photorefractivity, as well as very important technological features - ability to stay under photolithography, material engineering to change some physical or chemical properties which do not influence others parameters and simple film technology. Some weaknesses such as the lack of stability under chemical environment could be avoided by encapsulating with other more stable polymers. With all these features in mind we suggest new structures of Spatial Light Arrayed Modulator (SLAM) for modulation of light beams with 2-dimentional access to the each of pixels in it.
Connectivity concepts in neuronal network modeling
Authors: Senk Johanna , Kriener Birgit , Djurfeldt Mikael , Voges Nicole , Jiang Han-Jia , Schüttler Lisa , Gramelsberger Gabriele , Diesmann Markus , Plesser Hans E. , van Albada Sacha J.
Published: September 2022

Sustainable research on computational models of neuronal networks requires published models to be understandable, reproducible, and extendable. Missing details or ambiguities about mathematical concepts and assumptions, algorithmic implementations, or parameterizations hinder progress. Such flaws are unfortunately frequent and one reason is a lack of readily applicable standards and tools for model description. Our work aims to advance complete and concise descriptions of network connectivity but also to guide the implementation of connection routines in simulation software and neuromorphic hardware systems. We first review models made available by the computational neuroscience community in the repositories ModelDB and Open Source Brain, and investigate the corresponding connectivity structures and their descriptions in both manuscript and code. The review comprises the connectivity of networks with diverse levels of neuroanatomical detail and exposes how connectivity is abstracted in existing description languages and simulator interfaces. We find that a substantial proportion of the published descriptions of connectivity is ambiguous. Based on this review, we derive a set of connectivity concepts for deterministically and probabilistically connected networks and also address networks embedded in metric space. Beside these mathematical and textual guidelines, we propose a unified graphical notation for network diagrams to facilitate an intuitive understanding of network properties. Examples of representative network models demonstrate the practical use of the ideas. We hope that the proposed standardizations will contribute to unambiguous descriptions and reproducible implementations of neuronal network connectivity in computational neuroscience.
Architect: A tool for aiding the reconstruction of high-quality metabolic models through improved enzyme annotation
Authors: Nursimulu Nirvana , Moses Alan M. , Parkinson John
Published: September 2022

Constraint-based modeling is a powerful framework for studying cellular metabolism, with applications ranging from predicting growth rates and optimizing production of high value metabolites to identifying enzymes in pathogens that may be targeted for therapeutic interventions. Results from modeling experiments can be affected at least in part by the quality of the metabolic models used. Reconstructing a metabolic network manually can produce a high-quality metabolic model but is a time-consuming task. At the same time, current methods for automating the process typically transfer metabolic function based on sequence similarity, a process known to produce many false positives. We created Architect, a pipeline for automatic metabolic model reconstruction from protein sequences. First, it performs enzyme annotation through an ensemble approach, whereby a likelihood score is computed for an EC prediction based on predictions from existing tools; for this step, our method shows both increased precision and recall compared to individual tools. Next, Architect uses these annotations to construct a high-quality metabolic network which is then gap-filled based on likelihood scores from the ensemble approach. The resulting metabolic model is output in SBML format, suitable for constraints-based analyses. Through comparisons of enzyme annotations and curated metabolic models, we demonstrate improved performance of Architect over other state-of-the-art tools, notably with higher precision and recall on the eukaryote C. elegans and when compared to UniProt annotations in two bacterial species. Code for Architect is available at https://github.com/ParkinsonLab/Architect. For ease-of-use, Architect can be readily set up and utilized using its Docker image, maintained on Docker Hub.
Single-cell RNA sequencing reveals dysregulation of spinal cord cell types in a severe spinal muscular atrophy mouse model
Authors: Sun Junjie , Qiu Jiaying , Yang Qiongxia , Ju Qianqian , Qu Ruobing , Wang Xu , Wu Liucheng , Xing Lingyan
Published: September 2022

Although spinal muscular atrophy (SMA) is a motor neuron disease caused by the loss of survival of motor neuron (SMN) proteins, there is growing evidence that non-neuronal cells play important roles in SMA pathogenesis. However, transcriptome alterations occurring at the single-cell level in SMA spinal cord remain unknown, preventing us from fully comprehending the role of specific cells. Here, we performed single-cell RNA sequencing of the spinal cord of a severe SMA mouse model, and identified ten cell types as well as their differentially expressed genes. Using CellChat, we found that cellular communication between different cell types in the spinal cord of SMA mice was significantly reduced. A dimensionality reduction analysis revealed 29 cell subtypes and their differentially expressed gene. A subpopulation of vascular fibroblasts showed the most significant change in the SMA spinal cord at the single-cell level. This subpopulation was drastically reduced, possibly causing vascular defects and resulting in widespread protein synthesis and energy metabolism reductions in SMA mice. This study reveals for the first time a single-cell atlas of the spinal cord of mice with severe SMA, and sheds new light on the pathogenesis of SMA.