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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Ultra-thin photonic crystal slab metalenses [Invited]

We report a novel ultra-thin metalens design based on photonic crystal slab (PCS) resonance modes. We experimentally verified with a metalens structure based on amorphous silicon on a quartz material platform by implementing the optical guided resonance on the PCS. The PCS metalens designs feature an ultra-thin device layer of about 160 nm at an operation wavelength of 940 nm. A full 2π transmission phase transition is realized by varying the air hole sizes at the design wavelength. Metalens devices with different phase change gradients were designed and fabricated to achieve different NAs. A maximum of 86.4% focusing efficiency is achieved. Imaging capabilities are characterized, and clear images are observed within the field of view. The PC resonance-based phase modulation design can be applied to optical beam manipulation, phase plate design, imaging, and laser beam formation applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2025

Beam combining of high-power terahertz lasers with semiconductor metasurface gratings

Spectral beam combining (SBC) of an array of single-mode lasers has the potential for realizing a chip-scale electrically tunable multispectral laser source without any moving parts and with emission at closely spaced discrete frequencies. Here, we demonstrate SBC of an array of single-mode THz quantum-cascade lasers (QCLs) with small frequency spacing. Semiconductor-based metasurface THz blazed gratings are developed for integration with QCLs in a compact cryocooler setup. Single-lobed beams of four QCLs emitting around 3.2 THz and spectrally separated by ~14 GHz are combined to achieve collinear propagation of spatially overlapped and collimated beams in the far field with ≲ 0.1° of pointing error. Peak optical power in the range 50–100 mW is detected from each of the QCLs after combining. The dense frequency spacing in our method provides a pathway to incorporate tens of QCLs on a chip to realize a high-power discretely tunable THz laser source for applications in THz spectroscopy.

Jia, Fei [Lehigh Univ., Bethlehem, PA (United Stat↗
DOE OSTI2026

Redefining precision interferometry and spectroscopy with high-performance optical interference coatings

High-performance optical interference coatings have transformed precision interferometry and spectroscopy by enabling unparalleled control over light–matter interactions. This review explores recent innovations in ion-beam sputtered amorphous dielectric, as well as substrate-transferred crystalline coatings, and their impact on systems at the forefront of precision metrology. These state-of-the-art coating techniques generate multilayers with ultralow optical losses, yielding mirrors with exceptional reflectivity. Refinements in their noise performance push the ultimate limits of sensitivity, resolution, and stability in demanding laser-based metrology applications. These technologies underpin the most advanced timekeeping and spatial measurement tools, enabling high-finesse reference cavities for the world’s most precise optical atomic clocks and low-noise reflective test masses for km-baseline gravitational-wave detectors. Emerging hybrid designs combining these techniques expand access to the mid-infrared spectral region, enabling the first ultralow-optical-loss coatings in the 3000–5000 nm wavelength range for enhanced spectroscopy and trace-gas detection. We highlight how these technologies redefine coating performance metrics and set new benchmarks in quantum science, fundamental physics, and precision optical sensing.

Cole, Garrett D. [University of Arizona, Tucson, A↗
DOE OSTI2020

Foams in Hohlraums

Foam materials are starting to find application in laser-heated hohlraums used to drive inertial confinement fusion (ICF) implosions. The disparate scales of the solid foam elements (nm) compared to the typical problem scale (mm) make it expensive to resolve the individual foam elements in hydrodynamic calculations. In this project we developed two new models for treating foam materials – a 3D hydrodynamic model that treats the foam as bits of pre-expanded solid material separated by voids, and a subgrid model that captures the essential physics of laser-heated foams without requiring resolution of the individual solid elements. We also explored the microphysics of the transition from interpenetrating kinetic behavior to fully-collisional fluid-like behavior during the early time heating and expansion of foam elements through a combination of single-fluid and multi-fluid hydrodynamics calculations and particle-in-cell calculations. The model was benchmarked against these calculations and against experimental data on laser-heated chemical and additive-manufactured (AM) foams. Since there was no existing data on laser-heated AM foams, we performed the first experiments on such foams at the Jupiter Laser Facility. Samples of three different types of printed AM foams were heated using a single 0.5 micron laser. The foam densities ranged from 10 to 100 mg/cc (supercritical for 0.5 micron light). We measured the backscattered light (power and spectrum), the transmitted light, and the time-integrated temperature of the foam samples. This benchmarked subgrid foam model is a new capability that should allow routine calculation of ICF designs using foam elements, potentially opening up a new design space.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Measurement of electron density and temperature in plasmas

Application of two laser wavelengths passing through plasma measures electron density and temperature. Function depends on determining absorption of light at two wavelengths. Nature of reaction is explained and schematic diagram of equipment is included.

Billman, K. W.↗
NASA NTRS1971

Lidar applications to pollution studies.

This paper discusses the application of lidar (laser radar) to the measurement of air pollution. Lidar techniques and instrumentation utilizing elastic, Raman, and fluorescence scattering are discussed. Data showing measurements of the mixing of particulate pollutants in the atmosphere are presented. These data include: simultaneous two-wavelength results, isopleths showing the temporal dynamics of particulate mixing, measurements of the top of the earth's mixing layer, and measurements in a valley with restricted circulation and mixing. All measurements are compared with simultaneous radiosonde and/or aircraft-mounted temperature probe support. In addition, a second generation lidar system presently under development is described.

Mccormick, M. P.↗
NASA NTRS1974

Wavelength-selective, sequential Q-switching laser cavity

Single-frequency continuous output of laser is converted into series of high-power laser pulses at high repetition rates. Applications include pollutant detection by absorption, laser gain measurements at discrete wavelengths, laser propagation measurement, and laser plasma diagnostics.

Allario, F.↗
NASA NTRS1974

Velocity lag of solid particles in oscillating gases and in gases passing through normal shock waves

The velocity lag of micrometer size spherical particles is theoretically determined for gas particle mixtures passing through a stationary normal shock wave and also for particles embedded in an oscillating gas flow. The particle sizes and densities chosen are those considered important for laser Doppler velocimeter applications. The governing equations for each flow system are formulated. The deviation from Stokes flow caused by inertial, compressibility, and rarefaction effects is accounted for in both flow systems by use of an empirical drag coefficient. Graphical results are presented which characterize particle tracking as a function of system parameters.

Maxwell, B. R.↗
NASA NTRS1974

A facsimile system using room-temperature injection-laser scanning

This paper reports the first use of CW room-temperature injection lasers in a scanning facsimile system. The document reader can resolve about 2000 spots in each horizontal line of its raster scan, which is close to the performance attained using an He-Ne gas laser. The results obtained thus suggest that these small, efficient lasers can replace gas lasers in many applications.

Goedertier, P. V.↗
NASA NTRS1978

Thermal compensator for helium refrigerators

Closed-cycle helium refrigerator sensor generates negative-feedback control signals that drive heating diode to maintain temperature stability. Temperature-sensing diode and heating diode are mounted on heat sink that provides conductive path between load and cold tip. Method is applicable to other temperature-control applications, such as laser equipment, electronic instruments, and computer systems.

Hillman, J. J.↗
NASA NTRS1979

Is lunar ranging a viable component in a next-generation earth rotation service

The present actuality of the application of lunar laser ranging to the problem of the experimental determination of earth's rotation is discussed. The current status of the 'Earth Rotation from Lunar Distances' (EROLD) program is briefly summarized. Some results obtained up to 1978 for UT0 determinations are noted, and the situation regarding stations in Australia, France, West Germany, Japan, the United States, and the USSR is reviewed.

Mulholland, J. D.↗
NASA NTRS1980

Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

Levine, J. S.↗
NASA NTRS1979

Space optics; Proceedings of the Seminar, Huntsville, Ala., May 22-24, 1979

The seminar focused on infrared systems, the space telescope, new design for space astronomy, future earth resources systems, and planetary systems. Papers were presented on infrared astronomy satellite, infrared telescope on Spacelab 2, design alternatives for the Shuttle Infrared Telescope Facility, Spacelab 2 infrared telescope cryogenic system, geometrical theory of diffraction and telescope stray-light analysis, Space Telescope scientific instruments, faint-object spectrograph for the Space Telescope, light scattering from multilayer optics, bidirectional reflectance distribution function measurements of stray light suppression coatings for the Space Telescope, optical fabrication of a 60-in. mirror, interferogram analysis for space optics, nuclear-pumped lasers for space application, geophysical fluid flow experiment, coherent rays for optical astronomy in space, optical system with fiber-optical elements, and Pioneer-Venus solar flux radiometer.

Wyman, C. L.↗
NASA NTRS1980

Convolution of a Doppler line by a Gaussian instrument function

A simple and direct method is obtained for assessing the distortion of a Doppler line by a Gaussian instrument function. It is suggested that a close approximation to the width of a Gaussian instrument function, or an almost Gaussian function, may be obtained by measuring a line with a Doppler absorption coefficient. The method is applicable to diode laser measurements, and may be used whenever a Gaussian instrument function is a reasonable approximation to real conditions

Fridovich, B.↗
NASA NTRS1985

Lidar profiling of thermodynamic properties of the atmosphere

Principles and applications of pulsed laser methods for temperature, pressure, density, and humidity measurements in the altitude range 0-100 km are discussed. The differential absorption lidar (DIAL) method requires that at least one of the transmitted laser pulses be carefully tuned onto an absorption feature of the species, whereas Raman backscatter methods do not require tunability. OH and Na fluorescence require tuning of the excitation, and are the most suitable methods for high altitude where the atomic and molecular reemission is relatively unquenched by collisions.

Wilkerson, T. D.↗
NASA NTRS1986

The microwave and far-infrared spectra of the O-(18)H radical

Far-infrared laser magnetic resonance (LMR) spectroscopy was used to calculate the frequencies, wavelengths, and line strengths for transitions of O-(18)H molecules at microwave and far-infrared frequencies. In this experiment, a molecular transition frequency is tuned into coincidence with that of a fixed frequency laser by the application of a variable magnetic field. The O-(18)H radicals, detected in natural abundance (0.20 percent), were produced by the reaction of hydrogen atoms with nitrogen dioxide. These data together with microwave frequencies ascertained by Gottlieb, Redford, and Smith (1974) were used to determine the parameters of an effective Hamiltonian. Rotational levels up to J = 5.5 were involved. Results are indicated schematically and the low-lying energy levels of O-(18)H are shown. It is concluded that the frequencies of transitions between levels studied directly in the LMR experiment are reliable.

Comben, E. R.↗