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Results for “Optical devices”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Octupole moment driven free charge generation in partially chlorinated subphthalocyanine for planar heterojunction organic photodetectors

In this study, high-performance organic photodetectors are presented which utilize a pristine chlorinated subphthalocyanine photoactive layer. Optical and optoelectronic analyses indicate that the device photocurrent is primarily generated through direct charge generation within the chlorinated subphthalocyanine layer, rather than exciton separation at layer interfaces. Molecular modelling suggests that this direct charge generation is facilitated by chlorinated subphthalocyanine high octupole moment (-80 DÅ 2 ), which generates a 200 meV shift in molecular energetics. Increasing the thickness of chlorinated subphthalocyanine leads to faster response time, correlated with a decrease in trap density. Notably, photodetectors with a 50 nm thick chlorinated subphthalocyanine photoactive layer exhibit detectivities approaching 10 13 Jones, with a dark current below 10 -7 A cm -2 up to -5 V. Based on these findings, we conclude that high octupole moment molecular semiconductors are promising materials for high-performance organic photodetectors employing single-component photoactive layer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Reanalysis of Experimental Determinations of Polariton-Polariton Interactions in Microcavities

The polariton-polariton interaction strength is an important parameter for all kinds of applications using the nonlinear properties of polaritons, such as optical switching and single-photon blockade devices. In this paper, we review and compare the results of a series of experiments on polariton-polariton interactions in GaAs/AlxGa1-xAs microcavity polariton structures and present an updated analysis of these experiments. We show that not just the energy shift of the spectral lines but also the results of measurements sensitive to the polariton scattering rate are important for the calibration of the interaction parameter at low excitation density. We find that when adjustments are made to correct for recent understanding of the experiments, the value of the interaction parameter at low density is lower than previous reported, but still significantly higher than theoretically predicted.

CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SU↗
DOE OSTI2023

Interface-independent sound speed and thermal conductivity of atomic-layer-deposition-grown amorphous AlN / Al 2 O 3 multilayers with varying oxygen composition

Dielectric amorphous multilayers (AMLs) play a critical role in a wide array of technologies such as optical coatings, nanoelectronics, energy harvesting, and recovery devices. However, despite their wide applications, a robust understanding of the effect of the interplay between chemical and structural disorder on the thermal properties of AMLs is still lacking. Therefore, in this paper, we experimentally and numerically investigate the effects of composition and interface density on the sound speed and thermal conductivity of a series of amorphous aluminum nitride and aluminum oxide multilayers grown via plasma-enhanced atomic layer deposition. To systematically change the composition, the oxygen content of the AMLs is proportionally varied with interface density during growth. We find that the longitudinal sound speed of these AMLs is dictated by the oxygen content instead of the number of interfaces. The thermal conductivity, in contrast, is dictated by both interface density and oxygen content. The interfaces act to decrease the thermal conductivity, whereas the oxygen content increases the thermal conductivity. Due to the competing influence of the interfaces and oxygen content, the thermal conductivity of the AMLs remains nearly constant as a function of interface density. Furthermore, our study provides crucial insights into the effect of the interplay of composition and interfaces on the sound speed and thermal conductivity of AMLs.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Quantum Random Number Generator (QRNG)

The Los Alamos QRNG is a hardware-based high-performance Random Number Generator capable of generating 200 Mbit/s or more of true random numbers. The device harvests entropy from fluctuations in an optical source that arise from quantum mechanical properties of light. These quantum effects are irreducibly random; the resulting numbers are unpredictable and beyond the influence of any adversary. Qrypt, Inc., launched in 2017, has amassed multiple quantum entropy sources to create high-quality random keys at scale. The company is engaging with Los Alamos through license and a Cooperative Research and Development Agreement to facilitate the transition of QRNG technology and deploy the technology into the marketplace.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Leveraging Spin-Orbit Coupling in Ge/SiGe Heterostructures for Quantum Information Transfer

Hole spin qubits confined to lithographically - defined lateral quantum dots in Ge/SiGe heterostructures show great promise. On reason for this is the intrinsic spin - orbit coupling that allows all - electric control of the qubit. That same feature can be exploited as a coupling mechanism to coherently link spin qubits to a photon field in a superconducting resonator, which could, in principle, be used as a quantum bus to distribute quantum information. The work reported here advances the knowledge and technology required for such a demonstration. We discuss the device fabrication and characterization of different quantum dot designs and the demonstration of single hole occupation in multiple devices. Superconductor resonators fabricated using an outside vendor were found to have adequate performance and a path toward flip-chip integration with quantum devices is discussed. The results of an optical study exploring aspects of using implanted Ga as quantum memory in a Ge system are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Quantum Random Number Generator (QRNG)

The Los Alamos Quantum Random Number Generator (QRNG) is a hardware-based, high-performance Random Number Generator capable of generating 200 Mbit/s or more of true random numbers. Like flipping a coin, it is very much random and essential for information security like encrypting data on the internet, checking email, or purchasing something from an online vendor. The device harvests entropy from fluctuations in an optical source that arise from quantum mechanical properties of light. Qrypt, Inc., a company launched in 2017, began making strategic investments and developing partnerships to advance cutting-edge quantum hardware solutions. One of those key investments was licensing QRNG from Los Alamos and subsequently collaborating with advanced quantum materials and technology researcher Dr. Raymond Newell to create high-quality random keys at scale.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Effect of Solvent on Fluorescence Emission from Polyethylene Glycol-Coated Graphene Quantum Dots under Blue Light Illumination

To explore aggregate-induced emission (AIE) properties, this study adopts a one-pot hydrothermal route for synthesizing polyethylene glycol (PEG)-coated graphene quantum dot (GQD) clusters, enabling the emission of highly intense photoluminescence under blue light illumination. The hydrothermal synthesis was performed at 300 °C using o-phenylenediamine as the nitrogen and carbon sources in the presence of PEG. Three different solvents, propylene glycol methyl ether acetate (PGMEA), ethanol, and water, were used for dispersing the PEG-coated GQDs, where extremely high fluorescent emission was achieved at 530–550 nm. It was shown that the quantum yield (QY) of PEG-coated GQD suspensions is strongly dependent on the solvent type. The pristine GQD suspension tends to be quenched (i.e., QY: ~1%) when dispersed in PGMEA (aggregation-caused quenching). However, coating GQD nanoparticles with polyethylene glycol results in substantial enhancement of the quantum yield. When investigating the photoluminescence emission from PEG-coated GQD clusters, the surface tension of the solvents was within the range of from 26.9 to 46.0 mN/m. This critical index can be tuned for assessing the transition point needed to activate the AIE mechanism which ultimately boosts the fluorescence intensity. The one-pot hydrothermal route established in this study can be adopted to engineer PEG-coated GQD clusters with solid-state PL emission capabilities, which are needed for next-generation optical, bio-sensing, and energy storage/conversion devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1974

Stellar interferometer for figure sensing of orbiting astronomical telescopes

An interferometric device designed to be located in the focal plane of a large astronomical telescope is presented. The prime application is for the forthcoming large space telescope. The device is to perform interferometry on the optical wavefront arising from a single star after it has propagated through the telescope. The concept of a focal plane figure sensor has been experimentally verified by fabricating and testing an operating laboratory breadboard figure sensor. A set of linear independent control equations are derived that define the operations for utilizing a focal plane figure sensor in the control loops for the positioning of the secondary mirror and for the active control of the primary mirror optical figure. A number of scientific experiments that could be performed with the interferometer are also briefly discussed.

Peters, W. N.↗
NASA NTRS1981

Compact table-tilting mechanism

Optical components are oriented precisely by motorized device for manipulating objects attached to plane tilt table. Mechanism is compact, simple, and has low backlash. It consists of drive motor, rotatable disk, rigid link, and table. Motor rotates about vertical axis, and motion is converted through disk and rigid link to rotation of table about perpendicular axis.

Mitchell, F. R.↗
NASA NTRS1980

Submillimeter local oscillators for heterodyne spectroscopy

The major technological innovations in continuous wave (CW) submillimeter sources which are specifically suitable for application as local oscillators in heterodyne systems are reviewed. A description of the various sources is given which underscores the general principles and operating features for each type of device. Particular emphasis is placed on CW optically pumped lasers, which have had a dramatic impact as widely available sources of narrow linewidth coherent radiation. The state-of-the-art is summarized for these lasers and performance data are presented for several local oscillator packages. Optically pumped lasers are then compared and contrasted with other competing sources such as backward wave oscillators, IMPATT diodes, and Josephson junctions. By comparing their advantages and limitations for use as local oscillators, the potential applications of these different sources are projected. The prospects for increased tunability, reliability, and scalability are briefly considered, and several novel techniques for generating partially tunable radiation using Schottky diode mixers or CW Raman lasers are highlighted.

Danielewicz, E. J., Jr.↗
NASA NTRS1980

Pointing and control for planetary spacecraft - The first twenty years

The evolution of guidance and control systems for United States planetary and unmanned lunar spacecraft over the last 20 years is traced. The characteristics of the guidance and control systems used on spacecraft from the Range lunar impactor to the planned Galileo Jupiter orbiter and entry probe are surveyed, with attention given to the uses of three-axis stabilized, spin-stabilized and dual-spin designs. System performance trends that have evolved to meet the increasing science and mission requirements of the spacecraft are considered in the areas of attitude references, control consumables, dynamics and system modeling, thrust vector control, optical navigation, manuever turns, maneuver velocity control, instrument pointing, and antenna pointing. Hardware trends in optical sensors, inertial sensors, processing electronics, electromechanical devices, and system testing and reliability are also reviewed. The achievements represented by these advances are emphasized, and it is predicted that future developments will be in the areas of increased control system autonomy and performance requirements.

Pace, G. D.↗
NASA NTRS1981

Care, feeding, and use of charge-coupled device /CCD/ imagers at Palomar observatory

The paper describes the optical, mechanical, and electronic properties of the TI and RCA CCDs which have been applied to two-dimensional photometry and spectroscopy at Palomar. The drive, processing, and recording techniques are also discussed, and consideration is given to a focal conversion optical system, the Prime Focus Universal Extragalactic Instrument (PFUEI), which is used to more optimally match the Hale 5 meter plate scale. Calibration and data analysis are also examined.

Gunn, J. E.↗
NASA NTRS1983

Navigation of the Space Shuttle

Navigational systems and operations for the Space Shuttle are described. All navigational instrumentation is controlled from within the pressurized main cabin. Measurements of the state vector and the attitude are made with an inertial measurement unit (IMU), which uses data initialized at the moment of take-off. Orbital location is calculated in approximations using the initial propulsion conditions, models of the gravity field, and aerodynamic drag forces. Updates are periodically received from ground tracking stations. IMU continues attitude information, and additional references are made with an automated startracker device. Information can also be gathered by optical alignment, and future systems will include radar tracking in an approach mode. Deorbit is accompanied by IMU altitude measurements as well as calculations of altitude based on drag measurements. Barometric measurements begin at about 80,000 ft altitude. Signals are received from TACAN beginning at 145,000 ft, and the microwave scanning beam landing system is started at 20,000 ft. Various radionavigation systems are also employed in all flight phases.

Edwards, A., Jr.↗
NASA NTRS1984

Prospects for atomic frequency standards

The potentialities of different atomic frequency standards which are not yet into field operation, for most of them, but for which preliminary data, obtained in laboratory experiments, give confidence that they may improve greatly the present state of the art are described. The review will mainly cover the following devices: (1) cesium beam frequency standards with optical pumping and detection; (2) optically pumped rubidium cells; (3) magnesium beam; (4) cold hydrogen masers; and (5) traps with stored and cooled ions.

Audoin, C.↗
NASA NTRS1987

Radial image transfer by cylindrical, step-index optical waveguides

The theoretical extent of image transfer by perfect, cylindrical, step-index optical waveguides is examined. Azimuthal image structure is essentially removed by such waveguides, while substantial radial image structure is transmitted. The consequences of this behavior for optical-fiber image scramblers are discussed; such devices may be unsuitable for simple photometric applications but appear to be potentially useful in reducing zonal errors in slit spectroscopy.

Heacox, William D.↗