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All sources NASA NTRS DOE OSTI

NASA NTRS1998

Design and Performance of a Miniature Lidar Wind Profiler (MLWP)

The directional velocity of the wind is one of the most critical components for understanding meteorological and other dynamic atmospheric processes. Altitude-resolved wind velocity measurements, also known as wind profiles or soundings, are especially necessary for providing data for meteorological forecasting and overall global circulation models (GCM's). Wind profiler data are also critical in identifying possible dangerous weather conditions for aviation. Furthermore, a system has yet to be developed for wind profiling from the surface of Mars which could also meet the stringent requirements on size, weight, and power of such a mission. Obviously, a novel wind profiling approach based on small and efficient technology is required to meet these needs. A lidar system based on small and highly efficient semiconductor lasers is now feasible due to recent developments in the laser and detector technologies. The recent development of high detection efficiency (50%), silicon-based photon-counting detectors when combined with high laser pulse repetition rates and long receiver integration times has allowed these transmitter energies to be reduced to the order of microjoules per pulse. Aerosol lidar systems using this technique have been demonstrated for both Q-switched, diode-pumped solid-state laser transmitters (lambda = 523 nm) and semiconductor diode lasers (lambda = 830 nm); however, a wind profiling lidar based on this technique has yet to be developed. We will present an investigation of a semiconductor-laser-based lidar system which uses the "edge-filter" direct detection technique to infer Doppler frequency shifts of signals backscattered from aerosols in the planetary boundary layer (PBL). Our investigation will incorporate a novel semiconductor laser design which mitigates the deleterious effects of frequency chirp in pulsed diode lasers, a problem which has limited their use in such systems in the past. Our miniature lidar could be used on a future Mars lander and perhaps find its own niche in terrestrial applications due to its potential low cost an small size.

Cornwell, Donald M., Jr.↗

NASA NTRS2010

Two Micron Laser Technology Advancements at NASA Langley Research Center

An Independent Laser Review Panel set up to examine NASA s space-based lidar missions and the technology readiness of lasers appropriate for space-based lidars indicated a critical need for an integrated research and development strategy to move laser transmitter technology from low technical readiness levels to the higher levels required for space missions. Based on the review, a multiyear Laser Risk Reduction Program (LRRP) was initiated by NASA in 2002 to develop technologies that ensure the successful development of the broad range of lidar missions envisioned by NASA. This presentation will provide an overview of the development of pulsed 2-micron solid-state laser technologies at NASA Langley Research Center for enabling space-based measurement of wind and carbon dioxide.

Singh, Upendra N.↗

NASA NTRS1992

Broad-Area Laser Diode With Fiber-Optic Injection

Fiber-optic injection-locked broad-area laser diode features single-mode output via fiber-optic injection and serves as compact, rugged, high-power near-infrared source. Useful in free-space and fiber-optic communication links, as communication-receiver preamplifier, and pump source for solid-state lasers.

Hazel, Geoffrey↗

NASA NTRSDate not supplied

UV Laser Development for In Situ Planetary Lander Instruments

Mass and Raman spectrometers represent progressive analytical platforms for future in situ lander missions to explore the surface chemistry of planetary bodies across the Solar System. Europa, the Moon, and Mars are some of the primary targets for future NASA missions to search for extraterrestrial life and potentially habitable environments beyond Earth, further our understanding of the timing and formation of the Solar System and identify potentially viable economic resources such as water and/or valuable metal assets. The CORALS (Characterization of Ocean Residues And Life Signatures) and CRATER (Characterization of Regolith And Trace Economic Resources) instruments are UV laser-enabled OrbitrapTM mass spectrometers currently under development for prospective lander missions to Europa and the Moon, respectively. The Raman Mass Spectrometer (RAMS) is a dual wavelength (UV and visible) laser enabled hybrid instrument that incorporates laser desorption/ ionization mass spectrometry (LDMS) and micro-Raman microspectroscopy imaging (μRS) into a compact instrument package for multiple planetary missions to the inner and outer Solar System. The Pulse Laser Ablation Sampling and Mass Analysis (PLASMA) instrument combines a multi-wavelength laser (deep-UV to near-IR), plasma source, and collision cell with a heritage quadrupole mass spectrometer (QMS) to enable high precision trace element analyses for a future Lunar lander instrument. We report on the advancement of four compact, robust, and high technology readiness level (TRL) solid state lasers operating at wavelengths 213 nm, 266 nm, 515 nm, 532 nm and 1064 nm that serve as the sampling and ionization sources, for the CRATER, CORALS, RAMS and PLASMA investigations.

Molly Fahey↗

NASA NTRS2007

Lidar and Mission Parameter Trade Study of Space-Based Coherent Wind Measurement Centered on NASA's 2006 GWOS Wind Mission Study Parameters

The global measurement of vertical profiles of horizontal vector winds has been highly desired for many years by NASA, NOAA and the Integrated Program Office (IPO) implementing the National Polar-orbiting Operational Environmental Satellite Systems (NPOESS). Recently the global wind mission was one of 15 missions recommended to NASA by the first ever NRC Earth Sciences Decadal Survey. Since before 1978, the most promising method to make this space-based measurement has been pulsed Doppler lidar. The favored technology and technique has evolved over the years from obtaining line-of-sight (LOS) wind profiles from a single laser shot using pulsed CO2 gas laser technology to the current plans to use both a coherent-detection and direct-detection pulsed Doppler wind lidar systems with each lidar employing multiple shot accumulation to produce an LOS wind profile. The idea of using two lidars (hybrid concept) entails coherent detection using the NASA LaRC-developed pulsed 2-micron solid state laser technology, and direct detection using pulsed Nd:YAG laser technology tripled in frequency to 355 nm wavelength.

Kavaya, Michael J.↗

NASA NTRS1989

Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid large reabsorption losses. However, determination of the optimum Tm(3+) concentration required to ensure efficient energy transfer from Cr(3+) to Tm(3+) and from Tm(3+) to Ho(3+) has not been made in the Ho:Tm:CR:YAG crystal. The results obtained so far are given.

Choi, Young S.↗

NASA NTRS1992

Pulsed laser spectral measurement using a Fabry-Perot interferometer: Limits to resolution

We are developing a Doppler lidar system using the edge technique to measure atmospheric wind profiles. The edge technique requires a laser with a narrow spectral bandwidth and a high resolution optical filter. The lidar system will use a Nd:YAG laser operating at 1.064 microns and a high resolution Fabry-Perot interferometer for the edge filter. The Doppler shift measurement is made by locating the laser on the edge of the filter's spectral response function. Due to the steep slope on the edge, large changes in the filter transmission will be observed for small changes in frequency. The Doppler shift can be determined from a measurement of this change in filter transmission if the filter spectral response function in the region of the measurement is well known. Recently developed injection seeded solid state lasers have made near transform limited laser output readily available for lidar work. Injection-seeded Nd:YAG laser exhibit single mode output with smooth Gaussian temporal pulse shapes. Results of an experiment we conducted to evaluate the effects of a short Gaussian temporal input pulse on the spectral response of a high resolution Fabry-Perot interferometer are presented.

Notari, Anthony↗

NASA NTRS2000

Coherent Doppler Laser Radar: Technology Development and Applications

NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through headwind minimization. In addition to the airborne and space platforms, a coherent Doppler laser radar system in an unmanned aerial vehicle (UAV) could provide battlefield weather and target identification.

Kavaya, Michael J.↗

NASA NTRS1999

New Method for Calibration for Hyperspectral Pushbroom Imaging Systems

A new, easy-to-implement approach for achieving highly accurate spectral and radiometric calibration of array-based, hyperspectral pushbroom imagers is presented in this paper. The equivalence of the plane of the exit port of an integrating sphere to a Lambertian surface is utilized to provide a field-filling radiance source for the imager. Several different continuous wave lasers of various wavelengths and a quartz-tungsten-halogen lamp internally illuminate the sphere. The imager is positioned to "stare" into the port, and the resultant data cube is analyzed to determine wavelength calibrations, spectral widths of channels, radiometric characteristics, and signal-to-noise ratio, as well as an estimate of signal-to-noise performance in the field. The "smile" (geometric distortion of spectra) of the system can be quickly ascertained using this method. As the price and availability of solid state laser sources improve, this technique could gain wide acceptance.

Ryan, Robert↗

DOE OSTI2021

Demonstration of a compact, multi-joule, diode-pumped Tm:YLF laser

We report the demonstration of a diode-pumped Tm:YLF laser operating at 1.88 µm that produces pulse energies up to 3.88 J in 20 ns. The compact system consists of a Q-switched cavity-dumped oscillator generating 18 mJ pulses, which are then amplified in a 4-pass power amplifier. Energies up to 38.1 J were obtained with long-pulse amplifier operation. These results illustrate the high energy storage and extraction capabilities of diode-pumped Tm:YLF, opening the path to high peak and average power mid-infrared solid-state lasers

47 OTHER INSTRUMENTATION↗

NASA NTRS1994

Laser Initiated Ordnance (LIO) activities in NASA

Laser initiated ordnance appears to offer the advantages of greater reliability, enhanced safety, lighter, less costly products, and improvements in spacecraft system designs which can lead to higher operational efficiency. But the lack of flight demonstrations has prevented the application of this new technology into new programs. Hence, a three-phase technology program was initiated by NASA to provide flight proof of their technical and programmatic feasibility: flight demonstration aboard an unmanned commercial vehicle (Pegasus), use as a Space Shuttle payload, and the most demanding of applications, namely, solid rocket motor vehicle ignition and flight termination. The programs investigate, via flight demonstrations the use of fully solid state laser diode systems to reduce potential hazards imposed by stray electrical signals. Inadvertent ignition has proven to cause serious problems. While the current electromechanical have been made safe, the result has been complex systems. Now is the time to take advantage of this new technology to further enhance safety and reliability of spacecraft systems. Two of the three phases are underway; an announcement of opportunity for the third, a sounding rocket flight demonstration, was made at the workshop.

Schulze, Norman R.↗

NASA NTRS1984

Potential for coherent Doppler wind velocity lidar using neodymium lasers

Existing techniques for the frequency stabilization of Nd:YAG lasers operating at 1.06 micron, and the high-gain amplification of radiation at that wavelength, make possible the construction of a coherent Doppler wind velocity lidar using Nd:YAG. Velocity accuracy and range resolution are better at 1.06 micron than at 10.6 microns at the same level of the SNR. Backscatter from the atmosphere at 1.06 micron is greater than that at 10.6 microns by about 2 orders of magnitude, but the quantum-limited noise is higher by 100 also. Near-field attenuation and turbulent effects are more severe at 1.06 micron. In some configurations and environments, the 1.06-micron wavelength may be the better choice, and there may be technological advantages favoring the use of solid-state lasers in satellite systems.

Kane, T. J.↗

NASA NTRS1995

High spatial resolution atmospheric wind measurements with the edge technique

The edge technique is a new and powerful method for measuring small frequency shifts such as the Doppler shift of an atmospheric backscattered signal from a pulsed laser. The edge technique can be used for high spatial resolution, high accuracy ground and airborne wind measurements as well as high accuracy spaceborne wind measurements. We have recently made our first ground based wind measurements. These have a spatial resolution of 15 m and an accuracy of 25 cm/s and these measurements are presented in this paper. This is a unique capability and provides valuable information for studies of turbulent processes in the lower atmosphere. It could also be used for high sensitivity detection of wind shear and microbursts in the vicinity of airports. In addition, global wind measurements can be made with the edge technique from space with an accuracy of 1 m/s and a vertical resolution as high as 150 m in the boundary layer and 1 km through the troposphere. Such a system could make eyesafe wind measurements using well developed diode pumped solid state laser technology at 1.06 micron. Multi-pulse averaging would provide a spatially representative wind measurement.

Korb, C. Laurence↗

DOE OSTI2021

Submonolayer Quantum-Dot Based Saturable Absorber for Femtosecond Pulse Generation

Semiconductor saturable absorber mirrors (SESAMs) enable passive modelocking of several ultrafast solid-state lasers. Conventionally, SESAMs in the 1-µm wavelength range have employed InGaAs quantum wells (QWs) as absorbers. Here we demonstrate a SESAM based on InAs/GaAs submonolayer quantum dots (SML QDs) capable of generating femtosecond pulses by passively modelocking a vertical-external-cavity surface-emitting laser (VECSEL). Structural measurements are carried out to verify the quality and composition of the QDs. Modelocking experiments with a VECSEL and the QD SESAM in a ring cavity configuration yield pulses as short as 185 fs at 1025 nm. Compared to a traditional QW absorber, SML QD SESAMs exhibit ~ 25% faster recovery times. This also translates to slower power degradation rates or higher damage thresholds in SML QD SESAMs.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Ultranarrow electroluminescence from magnetic excitons in the van der Waals antiferromagnetic semiconductor NiPS 3

Electrically driven light emission from two-dimensional (2D) semiconducting materials has enabled numerous optoelectronic technologies, including light-emitting diodes, solid-state lasers, and single-photon sources for quantum communication. Here we report ultranarrow electroluminescence from the magnetic excitonic state of the van der Waals antiferromagnetic semiconductor NiPS 3 . This electroluminescence is enabled by the fabrication of gate-tunable NiPS 3 devices that remain electrically conductive below the antiferromagnetic ordering temperature of 155 K, ultimately allowing field-effect mobilities of 1.3 cm 2 V –1 s –1 and 4.5 cm 2 V –1 s –1 to be directly measured at room temperature and 7 K, respectively. By applying a high-frequency square wave voltage to the gate electrode of the resulting field-effect transistors, electroluminescence is capacitively induced from the magnetic excitons of NiPS 3 . Due to the coupling of these excitons with the underlying NiPS 3 antiferromagnetic order, the electroluminescence has an ultranarrow linewidth of 1 meV and a high degree of linear polarization (ρ = 0.78). In addition to facilitating fundamental studies of the coupling between spin states and excitons in van der Waals magnetic semiconductors, this work will accelerate the development of emerging 2D opto-spintronic applications.

two-dimensional materials↗

DOE OSTI2022

Reduced photothermal heating in diamonds enriched with H3 point defects

Solid-state laser refrigeration of semiconductors remains an outstanding experimental challenge. In this work, we show that, following excitation with a laser wavelength of 532 nm, bulk diamond crystals doped with H3 centers both emit efficient up-conversion (anti-Stokes) photoluminescence and also show significantly reduced photothermal heating relative to crystals doped with nitrogen–vacancy (NV) centers. The H3 center in diamond is a highly photostable defect that avoids bleaching at high laser irradiances of 10–70 MW/cm 2 and has been shown to exhibit laser action, tunable over the visible band of 500–600 nm. Here, the observed reduction of photothermal heating arises due to a decrease in the concentration of absorbing point defects, including NV-centers. These results encourage future exploration of techniques for H3 enrichment in diamonds under high-pressure, high-temperature conditions for the simultaneous anti-Stokes fluorescence cooling and radiation balanced lasing in semiconductor materials. Reducing photothermal heating in diamond through the formation of H3 centers also opens up new possibilities in quantum sensing via optically detected magnetic resonance spectroscopy at ambient conditions.

42 ENGINEERING↗

DOE OSTI2022

Ultrafast quantum dynamics driven by the strong space-charge field of a relativistic electron beam

Here, we illustrate how the Coulomb field of a highly relativistic electron beam can be shaped into a broadband pulse suitable for driving ultrafast and strong-field physics. In contrast to a solid-state laser, the Coulomb field creates a pulse which can be intrinsically synchronized with an x-ray free electron laser (XFEL), can have a cutoff frequency which is broadly tunable from THz to EUV, and which acts on target systems as a “half-cycle” impulse. Explicit examples are presented to emphasize how the unique features of this excitation can be a tool for novel science at XFEL facilities like the LCLS.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2024

Surface Ligand Effects on Energetics, Charge Transfer, and Stability at Interfaces Between Metal Halide Perovskites and Organic Semiconductors

Chemistry at organic-inorganic interfaces plays a major role in determining the performance of electronic and optoelectronic devices. Understanding, developing, and using surface chemistry is thus essential for creating improved and novel materials and devices. Organic metal halide perovskites (HPs) are inexpensive semiconductors that can be printed from solution to make efficient photovoltaic cells for harvesting solar energy, light emitting diodes for energy efficient solid-state lighting applications, solid-state lasers, and even spin selective devices with applications to quantum computing. To realize the potential of HPs, their surface chemistry and interfacial properties must be better understood and appropriately adjusted to meet the needs of the targeted application. For example, surface chemistry influences non-radiative recombination, which influences the efficiency of light emission and solar energy conversion, charge-carrier injection and extraction from optoelectronic devices, and material and device stability. This research project centered around determining how the surface chemistry of HP thin films and nanoparticles influences optical properties, charge transfer processes, energetics, and stability. In this project we characterized ligand binding strengths to HPs; determined how surface ligand chemistry influences photoluminescence properties, energetics, and charge transfer processes; determined that surface ligands often penetrate into HPs and uncovered methods of reducing surface ligand penetration through structural modifications; and discovered how interfacial energetics impact charge transfer processes and photovoltaic performance parameters. Overall, this research established important insights into how surface ligands interact with HPs to influence their optical properties, electronic properties, stability, and device level performance.

14 SOLAR ENERGY↗