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At least 55 records · Page 3

Stabilizing an optoelectronic microwave oscillator with photonic filters

This paper compares methods of active stabilization of an optoelectronic microwave oscillator (OEO) based on insertion of a source of optical group delay into an OEO loop. The performance of an OEO stabilized with either a high- optical cavity or an atomic cell is analyzed. We show that the elements play a role of narrow-band microwave filters improving an OEO stability.

Atomic clocks electromagnetically induced transpar

Space Flight Optoelectronics and Photonics Qualification

The Photonics group top level processes regarding development and qualification of space flight hardware for optoelectronic components along with our contributions and successes with LIDAR systems, space flight reliability heritage, and our testing capabilities are conveyed with this power point presentation.

Optical Systems

Space Flight LiDARs, Navigation & Science Instrument Implementations: Lasers, Optoelectronics, Integrated Photonics, Fiber Optic Subsystems and Components

For the past 25 years, the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center's Photonics Group in the Engineering Directorate has been substantially contributing to the flight design, development, production, testing and integration of many science and navigational instruments. The Moon to Mars initiative will rely heavily upon utilizing commercial technologies for instrumentation with aggressive schedule deadlines. The group has an extensive background in screening, qualifying, development and integration of commercial components for spaceflight applications. By remaining adaptable and employing a rigorous approach to component and instrument development, they have forged and fostered relationships with industry partners. They have been willing to communicate lessons learned in packaging, part construction, materials selection, testing, and other facets of the design and production process critical to implementation for high-reliability systems. As a result, this successful collaboration with industry vendors and component suppliers has enabled a history of mission success from the Moon to Mars (and beyond) while balancing cost, schedule, and risk postures. In cases where no commercial components exist, the group works closely with other teams at Goddard Space Flight Center and other NASA field centers to fabricate and produce flight hardware for science, remote sensing, and navigation applications. Summarized here is the last ten years of instrumentation development lessons learned and data collected from the subsystems down to the optoelectronic component level.

Detectors

Optoelectronics for Space Flight Instruments

The Photonics group top level processes regarding development and qualification of space flight hardware for optoelectronic components and optical systems along with our contributions and successes with LIDAR systems, space flight reliability heritage, and our testing capabilities are conveyed with this power point presentation.

Spaceflight

Highly Anisotropic Quasi‐Direct Organic Metal Halide Hybrids: A Platform for Polarization‐Sensitive Optoelectronics

Low-dimensional organic–inorganic metal halide hybrids (OMHHs) exhibit remarkable optical properties and enhanced environmental stability. We investigate a 1D OMHH with formula C 4 N 2 H 14 PbBr 4 , consisting of Pb–Br chains separated by organic cations, which shows a large Stokes shift (0.83 eV) and broadband emission. Through first-principles calculations and polarized Raman spectroscopy, we characterize the material's vibrational properties and identify the specific phonon modes that drive exciton self-trapping. Our novel GW/Bethe-Salpeter equation force formalism reveals that low-frequency phonons (∼ 100 cm −1 , primarily involving Pb–Br motions) couple strongly with excitons, with a remarkably high Huang-Rhys factor of 137 ± 4, and gives a pathway for ultrafast structural analysis during the absorption process. This phonon-exciton coupling mechanism explains the material's broadband emission and provides a pathway for controlling optical properties through vibrations and for tuning vibrations through optical excitations. The material also exhibits highly anisotropic optical properties and electronic transport, with bands that are dispersive along the Pb–Br chains but nearly flat in perpendicular directions, resulting in direction-dependent electrical conductivity that is calculated to be an order of magnitude higher along the chain direction and consistent with measurements. These combined properties make this system an excellent platform for polarization-sensitive optoelectronic devices.

36 MATERIALS SCIENCE

Deuteration Effects on the Physical and Optoelectronic Properties of Donor–Acceptor Conjugated Polymers

The significant differences in scattering cross sections between deuterium and protium are unique to neutron scattering techniques and have been a long-standing area of interest within the neutron scattering community. Researchers have explored selective deuteration to manipulate scattering contrast in soft matter systems, leading to the widespread use of deuterium labeling in materials development. As deuteration changes the atomic mass, it alters physical properties such as molecular volume, polarizability, and polarity, which in turn may affect noncovalent interactions and crystal ordering. Despite previous studies, there remains a limited understanding of how deuteration impacts donor–acceptor (DA) conjugated polymers. To address this, we synthesized deuterated DPP polymers and systematically investigated the effects of side-chain deuteration on their thermal stability, crystal packing, morphology, and optoelectronic properties. We found that deuteration increased the melting and crystallization temperatures of DPP polymers, although it did not significantly alter their morphology, molecular packing, or charge mobility. These properties were assessed by using atomic force microscopy (AFM), X-ray scattering, and thin-film transistor device measurements, respectively, for DPP polymers. Our work shows that deuterium labeling could be a powerful method for controlling scattering length density, enabling neutrons to study the structure and dynamics of conjugated polymers without impacting their electronic performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH

Synthetic Tuning of Exciton–Phonon Coupling in Janus WS 2(1-x) Se 2x Monolayers Revealed by Resonant Raman Excitation Spectroscopy for Optoelectronic Applications

Janus monolayers, such as WSSe, have broken out-of-plane symmetry and an intrinsic dipole moment, impacting exciton transport, lifetime, and phonon interactions while imbuing piezoelectric, photocatalytic, and Rashba spin-splitting properties to transition metal dichalcogenides (TMDs). The new properties of this atomically thin material can be used for optoelectronic device applications. As TMDs are converted into Janus monolayers, e.g., top selenization of WS2 to WSSe, the bandgap and structure smoothly evolve, impacting not only the formation of excitons but also their complex interactions with different phonon modes. Resonant Raman excitation profiles (REPs) are uniquely well-suited to reveal both excitonic transitions and exciton–phonon coupling. Here, the resonant REPs of $A^{'}_{1}$ WS 2 and A 1 WSSe modes are measured to understand the strength of their coupling with the A, B, and C excitonic bands of a WS2 monolayer throughout its stepwise transformation into Janus WSSe by pulsed laser deposition (PLD) of energetic selenium species. In situ Raman spectroscopy during deposition is used to controllably prepare stable intermediate Janus structures, WS 2(1-x) Se 2x (0 ≤ x ≤ 0.5), for ex situ measurement of their resonant REPs. As x increases, REPs reveal not only pronounced excitonic bands that gradually shift toward lower photon energies but also strong, mode-selective exciton–phonon coupling. First-principles resonant Raman simulations independently predict this spectral behavior and are shown capable of matching the spectrally broadened, experimentally observed REP profiles in this model system, indicating their strong predictive capability for future experiments. The combination of controlled synthesis, REP characterization, and predictive theory employed here demonstrates a powerful pathway to understand and ultimately tune exciton–phonon interactions for future quantum optical devices.

Janus monolayers

Optoelectronic polymer memristors with dynamic control for power-efficient in-sensor edge computing

Abstract As the demand for edge platforms in artificial intelligence increases, including mobile devices and security applications, the surge in data influx into edge devices often triggers interference and suboptimal decision-making. There is a pressing need for solutions emphasizing low power consumption and cost-effectiveness. In-sensor computing systems employing memristors face challenges in optimizing energy efficiency and streamlining manufacturing due to the necessity for multiple physical processing components. Here, we introduce low-power organic optoelectronic memristors with synergistic optical and mV-level electrical tunable operation for a dynamic “control-on-demand” architecture. Integrating signal sensing, featuring, and processing within the same memristors enables the realization of each in-sensor analogue reservoir computing module, and minimizes circuit integration complexity. The system achieves 97.15% fingerprint recognition accuracy while maintaining a minimal reservoir size and ultra-low energy consumption. Furthermore, we leverage wafer-scale solution techniques and flexible substrates for optimal memristor fabrication. By centralizing core functionalities on the same in-sensor platform, we propose a resilient and adaptable framework for energy-efficient and economical edge computing.

Optics

Prediction of BiS2-type pnictogen dichalcogenide monolayers for optoelectronics

Abstract In this work, we introduce a 2D materials family with chemical formula MX 2 (M={As, Sb, Bi} and X={S, Se, Te}) having a rectangular 2D lattice. This materials family has been predicted by systematic ab-initio structure search calculations in two dimensions. Using density-functional theory and many-body perturbation theory, we study the structural, vibrational, electronic, optical, and excitonic properties of the predicted MX 2 family. Our calculations reveal that the predicted SbX 2 and BiX 2 monolayers are stable while the AsX 2 layers exhibit an in-plane ferroelectric instability. All materials display strong excitonic effects and good optical absorption within the infrared-to-visible range. Hence, these monolayers can harvest solar energy and serve in optoelectronics applications. Furthermore, our results indicate that exfoliation of the predicted MX 2 monolayers from their bulk counterparts is experimentally viable.

Materials Science

Optoelectronic Proximity Sensor Finds Edges

Seams tracked for automatic control of welding. Optoelectronic system based on relatively simple array of optical proximity sensors locates edge of plate. Used to control automatic production machinery. System follows curved seams as well as straight ones, and neither special control programming nor precise initial positioning workpiece necessary for accurate tracking of seam.

Bejczy, Antal K.

Novel optoelectronic devices; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 2, 1987

The present conference on novel optoelectronics discusses topics in the state-of-the-art in this field in the Netherlands, quantum wells, integrated optics, nonlinear optical devices and fiber-optic-based devices, ultrafast optics, and nonlinear optics and optical bistability. Attention is given to the production of fiber-optics for telecommunications by means of PCVD, lifetime broadening in quantum wells, nonlinear multiple quantum well waveguide devices, tunable single-wavelength lasers, an Si integrated waveguiding polarimeter, and an electrooptic light modulator using long-range surface plasmons. Also discussed are backward-wave couplers and reflectors, a wavelength-selective all-fiber switching matrix, the impact of ultrafast optics in high-speed electronics, the physics of low energy optical switching, and all-optical logical elements for optical processing.

Adams, Michael J.

Optoelectronic signal processing for phased-array antennas; Proceedings of the Meeting, Los Angeles, CA, Jan. 12, 13, 1988

Papers are presented on fiber optic links for airborne satellite applications, optoelectronic techniques for broadband switching, and GaAs circuits for a monolithic optical controller. Other topics include the optical processing of covariance matrices for adaptive processors, an optical linear heterodyne matrix-vector processor, and an EHF fiber optic-based array. An adaptive optical signal processing architecture using a signed-digit number system is considered along with microwave fiber optic links for phased arrays.

Bhasin, Kul B.

Integrated Optoelectronic Interface

Proposed optoelectronic integrated-circuit device serves as "universal" or standard interface for transmission and reception of digital and analog signals in communication, data-processing, and control systems. Eliminates need for custom design of interface circuitry in sense that it embodies "master-chip" design easily adaptable to use with specific equipment. Includes directly modulated semiconductor laser to generate light signals for transmission along optical fiber; positive/intrinsic/negative, avalanche, or other photodiode to detect light signals received along another optical fiber;and driving, synchronizing, preamplifying, and signal-regenerating circuitry. Muliplexes electronic signals before transmission and/or demultiplexes electronic signals after reception.

Katz, Joseph

Optoelectronic Integrated Circuits For Neural Networks

Many threshold devices placed on single substrate. Integrated circuits containing optoelectronic threshold elements developed for use as planar arrays of artificial neurons in research on neural-network computers. Mounted with volume holograms recorded in photorefractive crystals serving as dense arrays of variable interconnections between neurons.

Psaltis, D.

Monolithic Optoelectronic Integrated Circuit

Monolithic optoelectronic integrated circuit (OEIC) receives single digitally modulated input light signal via optical fiber and converts it into 16-channel electrical output signal. Potentially useful in any system in which digital data must be transmitted serially at high rates, then decoded into and used in parallel format at destination. Applications include transmission and decoding of control signals to phase shifters in phased-array antennas and also communication of data between computers and peripheral equipment in local-area networks.

Bhasin, Kul B.