Search NASA⌕ Search

SEARCH · Search NASA

Results for “Quantum light”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Quantitative photoabsorption and fluorescence spectroscopy of H2S and D2S at 49-240 nm

Photoabsorption and fluorescence cross sections of H2S and D2S were measured in the 49-240 nm region using synchrotron radiation as a light source. Fluorescence from photoexcitation of H2S appears at 49-97 nm, but not in the long wavelength region. Fluorescence spectra were dispersed, and used to identify the emitters to be H2S(+) (A), SH(+)(A), and H(n greater than 2). The fluorescence quantum yield is about 6 percent. Photoexcitation of D2S at 49-96 nm produces fluorescence with a quantum yield of about 5 percent. The emitters are identified from the fluorescence spectra to be D2S(+)(A), SD(+)(A), and D(n greater than 2). The Franck-Condon factors for the SH(+) and SD(+) (A-X) transitions were determined. The SD(A-X) fluorescence was observed from photoexcitation of D2S at 100-151 nm, for which the fluorescence cross section and quantum yield were measured.

Lee, L. C.↗
NASA NTRS1973

O(D-1) production in ozone photolysis near 310 nm

Relative quantum yields of O(D-1)production, phi, in ozone photolysis from 275 nm to 334 nm were determined in the gas phase at 233 K. The O(D-1) was monitored by means of its reaction with isobutane to form isobutyl alcohol. The light source was a high pressure mercury lamp combined with a monochromator, with a bandwidth of 1.6 nm. The results show a constant phi below 300 nm, which is taken as unity on the basis of previous work. There is a very sharp fall-off in phi which is centered at 308 nm. At 313 nm phi is not greater than 0.1.

Lin, C.↗
NASA NTRS1992

The Second International Workshop on Squeezed States and Uncertainty Relations

This conference publication contains the proceedings of the Second International Workshop on Squeezed States and Uncertainty Relations held in Moscow, Russia, on 25-29 May 1992. The purpose of this workshop was to study possible applications of squeezed states of light. The Workshop brought together many active researchers in squeezed states of light and those who may find the concept of squeezed states useful in their research, particularly in understanding the uncertainty relations. It was found at this workshop that the squeezed state has a much broader implication than the two-photon coherent states in quantum optics, since the squeeze transformation is one of the most fundamental transformations in physics.

D Han↗
NASA NTRS2011

Volumetric 3D Display System with Static Screen

Current display technology has relied on flat, 2D screens that cannot truly convey the third dimension of visual information: depth. In contrast to conventional visualization that is primarily based on 2D flat screens, the volumetric 3D display possesses a true 3D display volume, and places physically each 3D voxel in displayed 3D images at the true 3D (x,y,z) spatial position. Each voxel, analogous to a pixel in a 2D image, emits light from that position to form a real 3D image in the eyes of the viewers. Such true volumetric 3D display technology provides both physiological (accommodation, convergence, binocular disparity, and motion parallax) and psychological (image size, linear perspective, shading, brightness, etc.) depth cues to human visual systems to help in the perception of 3D objects. In a volumetric 3D display, viewers can watch the displayed 3D images from a completely 360 view without using any special eyewear. The volumetric 3D display techniques may lead to a quantum leap in information display technology and can dramatically change the ways humans interact with computers, which can lead to significant improvements in the efficiency of learning and knowledge management processes. Within a block of glass, a large amount of tiny dots of voxels are created by using a recently available machining technique called laser subsurface engraving (LSE). The LSE is able to produce tiny physical crack points (as small as 0.05 mm in diameter) at any (x,y,z) location within the cube of transparent material. The crack dots, when illuminated by a light source, scatter the light around and form visible voxels within the 3D volume. The locations of these tiny voxels are strategically determined such that each can be illuminated by a light ray from a high-resolution digital mirror device (DMD) light engine. The distribution of these voxels occupies the full display volume within the static 3D glass screen. This design eliminates any moving screen seen in previous approaches, so there is no image jitter, and has an inherent parallel mechanism for 3D voxel addressing. High spatial resolution is possible with a full color display being easy to implement. The system is low-cost and low-maintenance.

Geng, Jason↗
NASA NTRS1985

Report from the Transfer-Laser Working Group

Light absorbing molecules and lasing molecules were discussed with regard to satisfying the following criteria for blackbody transfer lasers: (1) Good absorbers of blackbody radiation at 1500-2000 K; (2) Near resonant energy transfer from the absorbing gas to the lasant, provided not too many quantum number changes are required; (3) Dipole-dipole interactions for most efficient energy transfer; (4) Exothermic forward transfer reaction; (5) Polyatomic lasant molecules with at least two fundamental vibrational modes to ensure one or more states between the upper laser level and the ground state; (6) Polyatomic lasant molecules should not be so large or so complex that fast V-V relaxation occurs; (7) Metastable upper laser level for maintaining inversion, at least with respect to radiative and V-V decay; (8) Fast V-V into the upper laser level and out of the lower laser level; and (9) Lasing wavelengths less than 10.6 microns. Possible combinations of absorbers and lasants satisfying these criteria were discussed.

Meador, W. E.↗
NASA NTRS1989

X-ray calibration of a virtual phase 1024 x 1024 CCD

Results are presented on a calibration with X-rays of a front-illuminated virtual phase CCD with a 1024 x 1024 pixel array, performed as a part of the Solar-A preparation, which is a joint Japanese-U.S.-UK space project scheduled for a launch in August 1991. In the experiment, absolute quantum efficiency (QE) of a virtual CCD was measured at 14 wavelengths between 5.4 and 67.7 A, and its flat field responses to the illumination by C-K and Al-K X-rays were investigated together with its imaging properties in visible light. Higher than expected QE measurements were obtained at soft X-ray and EUV wavelengths; these are considered to be caused by fluorescence occurring in the absorbing layers on the CCD-entrance aperture.

Catura, R. C.↗
NASA NTRS2014

Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

The Chromospheric Lyman‐Alpha Spectro‐Polarimeter (CLASP) is a sounding rocket instrument which is currently being developed by NASA's Marshall Space Flight Center (MSFC) and the National Astronomical Observatory of Japan (NAOJ). The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman‐Alpha UV (121.6nm) light emitted by the Sun's Chromosphere to make measurements of the magnetic field in this region. In order to make accurate measurements of this effect, the performance characteristics of the three on‐board charge‐coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of no greater than 2 e(-)/DN, a noise level less than 25e(−), a dark current level which is less than 10e(−)/pixel/s, and a residual nonlinearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

Joiner, Reyann↗
NASA NTRS1995

Theoretical study of hole initiated impact ionization in bulk silicon and GaAs using a wave-vector-dependent numerical transition rate formulation within an ensemble Monte Carlo calculation

In this paper, calculations of the hole initiated interband impact ionization rate in bulk silicon and GaAs are presented based on an ensemble Monte Carlo simulation with the inclusion of a wave-vector-dependent numerical transition rate formulation. The ionization transition rate is determined for each of the three valence bands, heavy, light, and split-off, using Fermi's golden rule with a two-body, screened Coulomb interaction. The dielectric function used within the calculation is assumed to be wave-vector-dependent. Calculations of the field-dependent impact ionization rate as well as the quantum yield are presented. It is found from both the quantum yield results and examination of the hole distribution function that the effective threshold energy for hole initiated impact ionization is relatively soft, similar to that predicted for the corresponding electron initiated ionization events occur more frequently than either heavy or split-offf initiated ionization events in bulk silicon over the applied electric field strengths examined here, 250-500 kV/cm. Conversely,in GaAs, the vast majority of hole initated ionization events originate from holes within the split-off band.

Oguzman, Ismail H.↗
NASA NTRS2015

Induction of Oxidation in Living Cells by Time-Varying Electromagnetic Fields

We are studying how biological systems can harness quantum effects of time varying electromagnetic (EM) waves as the time-setting basis for universal biochemical organization via the redox cycle. The effects of extremely weak EM field on the biochemical redox cycle can be monitored through real-time detection of oxidation-induced light emissions of reporter molecules in living cells. It has been shown that EM fields can also induce changes in fluid transport rates through capillaries (approximately 300 microns inner diameter) by generating annular proton gradients. This effect may be relevant to understanding cardiovascular dis-function in spaceflight, beyond the ionosphere. Importantly, we show that these EM effects can be attenuated using an active EM field cancellation device. Central for NASA's Human Research Program is the fact that the absence of ambient EM field in spaceflight can also have a detrimental influence, namely via increased oxidative damage, on DNA replication, which controls heredity.

oxidation↗
NASA NTRS1973

Single photon detection and sub-nanosecond timing resolution with RCA C31034 photomultiplier

The very high quantum efficiencies and low dark count rates achieved with selected RCA C31034 photomultipliers make them attractive candidates for single photoelectron fast timing experiments. Single photoelectron plateau counting and a timing resolution of 0.60 nsec (FWHM) were obtained using fast amplifiers, constant fraction timing discriminators, and a pulsed light emitting diode. A redesign of the C31034 incorporating features of the very fast C31024 is suggested to yield even better timing resolution.

Reisse, R.↗
NASA NTRS1990

Spatial light modulators and applications III; Proceedings of the Meeting, San Diego, CA, Aug. 7, 8, 1989

Recent advances in the technology and applications of spatial light modulators (SLMs) are discussed in review essays by leading experts. Topics addressed include materials for SLMs, SLM devices and device technology, applications to optical data processing, and applications to artificial neural networks. Particular attention is given to nonlinear optical polymers, liquid crystals, magnetooptic SLMs, multiple-quantum-well SLMs, deformable-mirror SLMs, three-dimensional optical memories, applications of photorefractive devices to optical computing, photonic neurocomputers and learning machines, holographic associative memories, SLMs as parallel memories for optoelectronic neural networks, and coherent-optics implementations of neural-network models.

Efron, Uzi↗
NASA NTRS1991

Direct solar pumping of semiconductor lasers: A feasibility study

The primary goals of the feasibility study are the following: (1) to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space directly focused sunlight; and (2) to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or battery electrically pumping a current injection laser. With external modulation, such lasers may prove to be efficient sources for intersatellite communications. We proposed to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation for operation at low pump intensities. This report outlines our progress toward these goals. Discussion of several technical details are left to the attached summary abstract.

Anderson, Neal G.↗
NASA NTRS1992

Direct solar pumping of semiconductor lasers: A feasibility study

This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is summarized in Section 5, and information on publications resulting from this work is provided in Section 6.

Anderson, Neal G.↗
NASA NTRS1988

Fluorescence yields from photodissociative excitation of HCOOH, HCOOCH3, and CH3COOH in the vacuum-ultraviolet region

The photoexcitation processes of HCOOH, HCOOCH3, and CH3COOH were studied in the vacuum-ultraviolet region by using synchroton radiation and a pulsed discharge lamp as light sources. The absorption and fluorescence cross sections of these molecules were measured in the 106-250-nm region. Fluorescences were detected from photoexcitation of HCOOH and HCOOCH3, but not from CH3COOH. Fluorescence produced at 123.9 nm was dispersed and identified as the excited OH and HCOO radicals. Fluorescence quantum yields of HCOOH and HCOOCH3 increase with decreasing excitation wavelengths with maxima of 5 and 0.3 percent at 106 nm, respectively.

Suto, Masako↗
NASA NTRS1991

An abuttable CCD imager for visible and X-ray focal plane arrays

A frame-transfer silicon charge-coupled-device (CCD) imager has been developed that can be closely abutted to other imagers on three sides of the imaging array. It is intended for use in multichip arrays. The device has 420 x 420 pixels in the imaging and frame-store regions and is constructed using a three-phase triple-polysilicon process. Particular emphasis has been placed on achieving low-noise charge detection for low-light-level imaging in the visible and maximum energy resolution for X-ray spectroscopic applications. Noise levels of 6 electrons at 1-MHz and less than 3 electrons at 100-kHz data rates have been achieved. Imagers have been fabricated on 1000-Ohm-cm material to maximize quantum efficiency and minimize split events in the soft X-ray regime.

Burke, Barry E.↗
NASA NTRS1987

Optical investigation of highly strained InGaAs-GaAs multiple quantum wells

Low-temperature optical transmission spectra of several In(x)Ga(1-x)/GaAs strained MQWs with x = 0.13-0.19 and well widths of 85-213 A have been measured. The excitonic transitions up to 3C-3H were observed along with steplike structures corresponding to band-to-band transitions, identified as 1C-1L transitions. By fitting experimental results to the calculations, it is concluded that the light holes are in the GaAs barrier region (type II MQW), and the valence-band offset is determined to be 0.30. Attention is given to a possible system in which the transition from type I to type II for light holes might be observed.

Ji, G.↗
NASA NTRS1989

Optically controlled absorption modulator based on state filling of In(x)Ga(1-x)As/GaAs quantum wells

The first demonstration of an optically controlled absorption modulator based on state filling in a periodically doped In(x)Ga(1-x)As/GaAs multiple quantum well structure is reported. Differential absorption of approximately 10,000/cm is observed in the quantum wells of the test structure at saturation pump powers. Photoluminescence and time-resolved modulation measurements confirm the predicted behavior of carrier recombination and give a measure of enhanced carrier lifetime of approximately 1 ms. These initial results show the potential for developing these structures into optically addressed spatial light modulators.

Iannelli, J. M.↗
NASA NTRS1992

Workshop on Squeezed States and Uncertainty Relations

The proceedings from the workshop are presented, and the focus was on the application of squeezed states. There are many who say that the potential for industrial applications is enormous, as the history of the conventional laser suggests. All those who worked so hard to produce squeezed states of light are continuing their efforts to construct more efficient squeezed-state lasers. Quite naturally, they are looking for new experiments using these lasers. The physical basis of squeezed states is the uncertainty relation in Fock space, which is also the basis for the creation and annihilation of particles in quantum field theory. Indeed, squeezed states provide a unique opportunity for field theoreticians to develop a measurement theory for quantum field theory.

Han, Daesoo↗