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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Ultra-Long Distance BOTDA Sensor System Employing Hybrid Amplification and Advanced Noise Reduction Techniques

Brillouin Optical Time Domain Analysis (BOTDA) sensor system play a pivotal role in distributed sensing, which enables precise measurements of strain and temperature across extensive fiber lengths. Nonetheless, challenges emerge as distances grow due to signal attenuation and noise interference resulting in measurement errors. This research offers a comprehensive strategy to extend the sensing range of BOTDA systems beyond 10’s of kilometers while maintaining high spatial resolutions. Such enhanced sensing is realized through the integration of distributed Raman amplification, inline amplification using erbium-doped fiber amplifiers (EDFA), and advanced noise reduction techniques. Leveraging inherent redundancy in measured data as a function of frequency and fiber distance, the non-local means (NLM) filter removes noise while preserving essential physical information. This approach proves particularly advantageous in BOTDA systems, where accurate measurement of Brillouin scattering signals is paramount for long-range sensing, while concurrently safeguarding high spatial resolutions. In summary, this research has shown a holistic exploration of extending BOTDA's distance sensing capabilities up to 150 km with spatial resolutions of 8 meters.

Bhatta, Hari↗
NASA NTRS1994

Evolution of dynamo-generated magnetic fields in accretion disks around compact and young stars

Geometrically thin, optically thick, turbulent accretion disks are believed to surround many stars. Some of them are the compact components of close binaries, while the others are throught to be T Tauri stars. These accretion disks must be magnetized objects because the accreted matter, whether it comes from the companion star (binaries) or from a collapsing molecular cloud core (single young stars), carries an embedded magnetic field. In addition, most accretion disks are hot and turbulent, thus meeting the condition for the MHD turbulent dynamo to maintain and amplify any seed field magnetic field. In fact, for a disk's magnetic field to persist long enough in comparison with the disk viscous time it must be contemporaneously regenerated because the characteristic diffusion time of a magnetic field is typically much shorter than a disk's viscous time. This is true for most thin accretion disks. Consequently, studying magentic fields in thin disks is usually synonymous with studying magnetic dynamos, a fact that is not commonly recognized in the literature. Progress in studying the structure of many accretion disks was achieved mainly because most disks can be regarded as two-dimensional flows in which vertical and radial structures are largely decoupled. By analogy, in a thin disk, one may expect that vertical and radial structures of the magnetic field are decoupled because the magnetic field diffuses more rapidly to the vertical boundary of the disk than along the radius. Thus, an asymptotic method, called an adiabatic approximation, can be applied to accretion disk dynamo. We can represent the solution to the dynamo equation in the form B = Q(r)b(r,z), where Q(r) describes the field distribution along the radius, while the field distribution across the disk is included in the vector function b, which parametrically depends on r and is normalized by the condition max (b(z)) = 1. The field distribution across the disk is established rapidly, while the radial distribution Q(r) evolves on a considerably longer timescale. It is this evolution that is the subject of this paper.

Stepinski, Tomasz F.↗
NASA NTRS2012

670-GHz Schottky Diode-Based Subharmonic Mixer with CPW Circuits and 70-GHz IF

GaAs-based, sub-harmonically pumped Schottky diode mixers offer a number of advantages for array implementation in a heterodyne receiver system. Since the radio frequency (RF) and local oscillator (LO) signals are far apart, system design becomes much simpler. A proprietary planar GaAs Schottky diode process was developed that results in very low parasitic anodes that have cutoff frequencies in the tens of terahertz. This technology enables robust implementation of monolithic mixer and frequency multiplier circuits well into the terahertz frequency range. Using optical and e-beam lithography, and conventional epitaxial layer design with innovative usage of GaAs membranes and metal beam leads, high-performance terahertz circuits can be designed with high fidelity. All of these mixers use metal waveguide structures for housing. Metal machined structures for RF and LO coupling hamper these mixers to be integrated in multi-pixel heterodyne array receivers for spectroscopic and imaging applications. Moreover, the recent developments of terahertz transistors on InP substrate provide an opportunity, for the first time, to have integrated amplifiers followed by Schottky diode mixers in a heterodyne receiver at these frequencies. Since the amplifiers are developed on a planar architecture to facilitate multi-pixel array implementation, it is quite important to find alternative architecture to waveguide-based mixers.

Chattopadhyay, Goutam↗
NASA NTRS2016

NASA's Preparations for ESA's L3 Gravitational Wave Mission

Telescope Subsystem - Jeff Livas (GSFC): Demonstrate pathlength stability, straylight and manufacturability. Phase Measurement System - Bill Klipstein (JPL): Key measurement functions demonstrated. Incorporate full flight functionality. Laser Subsystem - Jordan Camp (GSFC): ECL master oscillator, phase noise of fiber power amplifier, demonstrate end-to-end performance in integrated system, lifetime. Micronewton Thrusters - John Ziemer (JPL): Propellant storage and distribution, system robustness, manufacturing yield, lifetime. Arm-locking Demonstration - Kirk McKenzie (JPL): Studying a demonstration of laser frequency stabilization with GRACE Follow-On. Torsion Pendulum - John Conklin (UF): Develop U.S. capability with GRS and torsion pendulum test bed. Multi-Axis Heterodyne Interferometry - Ira Thorpe (GSFC): Investigate test mass/optical bench interface. UV LEDs - John Conklin+ (UF): Flight qualify UV LEDs to replace mercury lamps in discharging system. Optical Bench - Guido Mueller (UF): Investigate alternate designs and fabrication processes to ease manufacturability. LISA researchers at JPL are leading the Laser Ranging Interferometer instrument on the GRACE Follow-On mission.

Midterm Assessment↗
DOE OSTI2020

High-power few-cycle Cr:ZnSe mid-infrared source for attosecond soft x-ray physics

The development of mid-infrared, high-energy pulses of extremely short pulse duration is of great importance to the strong-field physics community, as it enables extension of the high-harmonic cutoff towards the keV range of photon energies. Here we demonstrate a C r 2 + : Z n S e laser amplifier delivering 7 mJ, 100 fs pulses at 1 kHz repetition rate and 2.4 µm central wavelength with excellent energy stability and beam quality. These pulses are post-compressed to 39 fs, 6.2 mJ, and 115 GW peak power in a novel nonlinear compression scheme. The laser system was used to generate coherent soft x-ray radiation up to 0.6 keV covering the entire water window, which is of high importance for bio-relevant applications. The obtained results open a wide range of applications in nonlinear optics, attosecond and strong-field physics, and remote sensing.

Leshchenko, Vyacheslav E. (ORCID:0000000199708559)↗
DOE OSTI2020

Demonstration of a 2 ps, 5 TW peak power, long-wave infrared laser based on chirped-pulse amplification with mixed-isotope CO 2 amplifiers 2 amplifiers

We report generation of 5 TW peak power in a 2 ps pulse at 9.2 µm via chirped-pulse amplification (CPA) in mixed-isotope high-pressure CO 2 laser amplifiers. This represents the highest peak power in a single picosecond pulse format and the shortest pulse at terawatt peak power ever achieved in the long-wave infrared (LWIR) spectral range. Maximum demonstrated energy of the compressed pulse is 14 J and minimum period between shots is 20 s. The successful implementation of the chirped pulse amplification technique in a short-pulse gas laser opens a route to development of LWIR laser facilities with tens of terawatts of peak power, thus approaching the number of photons per optical cycle of current near-infrared laser systems based on solid-state active media.

43 PARTICLE ACCELERATORS↗
NASA NTRS2010

A Global Modeling Study on Carbonaceous Aerosol Microphysical Characteristics and Radiative Effects

Recently, attention has been drawn towards black carbon aerosols as a short-term climate warming mitigation candidate. However the global and regional impacts of the direct, indirect and semi-direct aerosol effects are highly uncertain, due to the complex nature of aerosol evolution and the way that mixed, aged aerosols interact with clouds and radiation. A detailed aerosol microphysical scheme, MATRIX, embedded within the GISS climate model is used in this study to present a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative effects. Our best estimate for net direct and indirect aerosol radiative flux change between 1750 and 2000 is -0.56 W/m2. However, the direct and indirect aerosol effects are quite sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative flux change can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Absorption of black carbon aerosols is amplified by sulfate and nitrate coatings and, even more strongly, by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative fluxeswhen sources with a large proportion of black carbon, such as diesel, are reduced; however reducing sources with a larger organic carbon component as well, such as bio-fuels, does not necessarily lead to a reduction in positive radiative flux.

Bauer, S. E.↗
NASA NTRSDate not supplied

Progress of 2.05 uM Fiber Laser Development for A Martian Co2 Dial

We have proposed a new concept for differential absorption lidar (DIAL) operating in the 2050 nm CO 2 absorption band for atmospheric CO 2 and pressure observations on Mars. This concept has earned us funding from NASA's PICASSO Program to advance 2050 nm fiber laser technology for future space applications. The laser design is an all-fiber master oscillator and power amplifier (MOPA) system. The master oscillator with pulse shaping and several stages of fiber preamplifiers has been built. Preliminary tests show the output pulse energy can reach 1 mJ, meeting our baseline goal. However, the current power amplifier design has an issue with undesired parasitic lasing at a different frequency, which exhausts pump energy and limits the laser energy. We have modified the power amplifier design to suppress parasitic lasing, and higher laser power energy is expected. To achieve high measurement accuracy, the laser frequency must be stabilized. A fraction of the master oscillator is split to lock the laser frequency to the center of the selected absorption line. The laser can then be shifted to a frequency far from the absorption line center, where extinction due to CO 2 and other trace gases is minimal, serving as the offline reference. The online wavelength is optimized at 2050.44156 nm, ensuring a CO 2 absorption optical depth (AOD) of approximately 1.1 at 3 km, which maximizes the signal-to-noise ratio (SNR) for measurements in the lower Martian atmosphere. At the conference, we will provide more details about this project and report on the progress of instrument development.

DIAL↗
DOE OSTI2020

Population inversion X-ray laser oscillator

Oscillators are at the heart of optical lasers, providing stable, transform-limited pulses. Until now, laser oscillators have been available only in the infrared to visible and near-ultraviolet (UV) spectral region. In this paper, we present a study of an oscillator operating in the 5- to 12-keV photon-energy range. We show that, using the Kα 1 line of transition metal compounds as the gain medium, an X-ray free-electron laser as a periodic pump, and a Bragg crystal optical cavity, it is possible to build X-ray oscillators producing intense, fully coherent, transform-limited pulses. As an example, we consider the case of a copper nitrate gain medium generating ~ 5 × 10 10 photons per pulse with 37-fs pulse length and 48-meV spectral resolution at 8-keV photon energy. Our theoretical study and simulation of this system show that, because of the very large gain per pass, the oscillator saturates and reaches full coherence in four to six optical-cavity transits. We discuss the feasibility and design of the X-ray optical cavity and other parts of the oscillator needed for its realization, opening the way to extend X-ray–based research beyond current capabilities.

47 OTHER INSTRUMENTATION↗
NASA NTRS1988

Integrated Solar Disk Oscillation Measurements Using the Magneto-Optical Filter: Tests with a Two Station Network

The magneto-optical filter (MOF) was used to get high and intermediate l-modes of solar oscillations. For very low l-modes the imaging capability of the MOF is still attractive since it allows a pixel by pixel intensity normalization. However, a crude attempt to get very low l power spectra from Dopplergrams obtained at Mt. Wilson gave noisy results. This means that a careful analysis of all the factors potentially affecting high resolution Dopplergrams should be accomplished. In order to better investigate this problem, a nonimaging channel using the lock-in amplifier technique was considered. Two systems are now operational, one at JPL and the other at University of Rome. Observations in progress are used to discuss the MOF stability, the noise level, and the possible application in asteroseismology.

Cacciani, Alessandro↗
NASA NTRS2012

Systematic Destruction of Electronic Parts for Aid in Electronic Failure Analysis

NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. Operational amplifiers and transistors are two examples of EEE parts critical to NASA missions that can fail due to electrical overstress (EOS). EOS is the result of voltage or current over time conditions that exceeds a component s specification limit. The objective of this study was to provide known voltage pulses over well-defined time intervals to determine the type and extent of damage imparted to the device. The amount of current was not controlled but measured so that pulse energy was determined. The damage was ascertained electrically using curve trace plots and optically using various metallographic techniques. The resulting data can be used to build a database of physical evidence to compare to damaged components removed from flight avionics. The comparison will provide the avionics failure analyst necessary information about voltage and times that caused flight or test failures when no other electrical data is available.

Decker, S. E.↗
NASA NTRS2011

All-Solid-State 2.45-to-2.78-THz Source

Sources in the THz range are required in order for NASA to implement heterodyne instruments in this frequency range. The source that has been demonstrated here will be used for an instrument on the SOFIA platform as well as for upcoming astrophysics missions. There are currently no electronic sources in the 2 3- THz frequency range. An electronically tunable compact source in this frequency range is needed for lab spectroscopy as well as for compact space-deployable heterodyne receivers. This solution for obtaining useful power levels in the 2 3- THz range is based on utilizing power-combined multiplier stages. Utilizing power combining, the input power can be distributed between different multiplier chips and then recombined after the frequency multiplication. A continuous wave (CW) coherent source covering 2.48 2.75 THz, with greater than 10 percent instantaneous and tuning bandwidth, and having l 14 W of output power at room temperature, has been demonstrated. This source is based on a 91.8 101.8-GHz synthesizer followed by a power amplifier and three cascaded frequency triplers. It demonstrates that purely electronic solid-state sources can generate a useful amount of power in a region of the electromagnetic spectrum where lasers (solid-state or gas) were previously the only available coherent sources. The bandwidth, agility, and operability of this THz source has enabled wideband, high-resolution spectroscopic measurements of water, methanol, and carbon monoxide with a resolution and signal-to-noise ratio unmatched by other existing systems, providing new insight in the physics of these molecules. Further - more, the power and optical beam quality are high enough to observe the Lamb-dip effect in water. The source frequency has an absolute accuracy better than 1 part in 1012, and the spectrometer achieves sub-Doppler frequency resolution better than 1 part in 108. The harmonic purity is better than 25 dB. This source can serve as a local oscillator for a variety of heterodyne systems, and can be used as a method for precision control of more powerful but much less frequency-agile quantum mechanical terahertz sources.

Mehdi, Imran↗
NASA NTRSDate not supplied

Insights and Observations From Operating A Laser Communication Terminal on the International Space Station (ISS)

The Integrated Laser Communication Relay Demonstration (LCRD) Low Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T) is the first user platform for NASA’s first laser communication relay, LCRD. ILLUMA-T is hosted on the International Space Station (ISS) as an external payload of the Japanese Experiment Module – Exposed Facility (JEM-EF) situated in slot 3. The LCRD payload is hosted on the STPSat-6 spacecraft, which orbits Earth in a geostationary orbit at position 112 W. The ILLUMA-T-to-LCRD system provides a bidirectional, space-to-ground laser communication relay link transferring data up to 1.2 Gbps utilizing two optical ground stations (OGS), OGS-1 in California and OGS-2 in Hawai’i. This paper describes lessons learned from operating the ILLUMA-T system and examines topics such as the end-to-end system availability, predictive versus actual ephemeris, acquisition adjustments, modem timing and handshaking, the terminal’s physical placement and accommodations, and experiment development, execution, and analysis. The authors of this paper operate both the LCRD and ILLUMA-T laser terminals on a daily basis including pass planning, procedure execution, acquisition analysis, and real-time terminal commanding and telemetry monitoring. LCRD is a joint project involving NASA Goddard Space Flight Center (GSFC), the California Institute of Technology Jet Propulsion Laboratory (JPL), and Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). The ILLUMA-T payload is managed by NASA GSFC in Greenbelt, Maryland whose partners include the ISS program office at NASA’s Johnson Space Center (JSC) in Houston, Texas; the Huntsville Operations Support Center (HOSC) at Marshall Space Flight Center (MSFC) in Huntsville, Alabama; the Glenn Research Center (GRC) in Cleveland, Ohio; and the MIT LL in Lexington, Massachusetts. ILLUMA-T is funded by the Space Communications and Navigation (SCaN) Program at NASA Headquarters in Washington, D.C.

Laser Communications↗
DOE OSTI2020

Optically pumped semiconductor laser based on a type-II CdS/ZnSe heterostructure

An optically pumped semiconductor laser based on a type-II CdS/ZnSe nanoheterostructure containing 10 quantum wells (QWs) was studied. The structure was grown by metal-organic vapour phase epitaxy on a GaAs substrate. The lifetime of electron-hole pairs at a low pump level was measured by luminescence decay to be ∼0 ns. The peak power of the microcavity semiconductor laser at room temperature and longitudinal pumping by a repetitively pulsed N{sub 2} laser was 7.2 W at a wavelength of 514 nm. The relatively low laser slope efficiency (0.35 %) is explained by amplified spontaneous emission propagating along the structure. The peak power and efficiency of the laser in the case of transverse pumping increase to 70 W and 3.5 %, respectively. (lasers)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2014

Ka-Band Link Study and Analysis for a Mars Hybrid RF/Optical Software Defined Radio

The integrated radio and optical communications (iROC) project at the NASA Glenn Research Center (GRC) is investigating the feasibility of a hybrid RF and optical communication subsystem for future deep space missions. The hybrid communications subsystem enables the advancement of optical communications while simultaneously mitigating the risk of infusion by combining an experimental optical transmitter and telescope with a reliable Ka-band RF transmitter and antenna. The iROC communications subsystem seeks to maximize the total data return over the course of a potential 2-year mission in Mars orbit beginning in 2021. Although optical communication by itself offers potential for greater data return over RF, the reliable Ka-band link is also being designed for high data return capability in this hybrid system. A daily analysis of the RF link budget over the 2-year span is performed to optimize and provide detailed estimates of the RF data return. In particular, the bandwidth dependence of these data return estimates is analyzed for candidate waveforms. In this effort, a data return modeling tool was created to analyze candidate RF modulation and coding schemes with respect to their spectral efficiency, amplifier output power back-off, required digital to analog conversion (DAC) sampling rates, and support by ground receivers. A set of RF waveforms is recommended for use on the iROC platform.

communication↗
NASA NTRS2003

Limits to the Indirect Aerosol Forcing in Stratocumulus

The indirect radiative forcing of aerosols is poorly constrained by the observational data underlying the simple cloud parameterizations in GCMs. signal of cloud response to increased aerosol concentrations from meteorological noise. Recent satellite observations indicate a significant decrease of cloud water in ship tracks, in contrast to an ensemble of in situ measurements showing no average change in cloud water relative to the surrounding clouds. Both results contradict the expectation of cloud water increasing in polluted clouds. We find through large-eddy simulations of stratocumulus that the trend in the satellite data is likely an artifact of sampling only overcast clouds. The simulations instead show cloud cover increasing with droplet concentrations. The simulations also show that increases in cloud water from suppressing drizzle by increased droplet concentrations are favored at night or at extremely low droplet concentrations. At typical droplet concentrations we find that the Twomey effect on cloud albedo is amplified very little by the secondary indirect effect of drizzle suppression, largely because the absorption of solar radiation by cloud water reduces boundary-layer mixing in the daytime and thereby restricts any possible increase in cloud water from drizzle suppression. The cloud and boundary layer respond to radiative heating variations on a time scale of hours, and on longer time scales respond to imbalances between large-scale horizontal advection and the entrainment of inversion air. We analyze the co-varying response of cloud water, cloud thickness, width of droplet size distributions, and dispersion of the optical depth, as well as the overall response of cloud albedo, to changes in droplet concentrations. We also dissect the underlying physical mechanisms through sensitivity studies. Ship tracks represent an ideal natural laboratory to extricate the

Ackerman, Andrew↗
DOE OSTI2020

Sub-Hertz resonance by weak measurement

Weak measurement (WM) with state pre- and post-selection can amplify otherwise undetectable small signals and thus has potential in precision measurement applications. Although frequency measurements offer the hitherto highest precision due to the stable narrow atomic transitions, it remains a long-standing interest to develop new schemes to further escalate their performance. Here, we demonstrate a WM-enhanced correlation spectroscopy technique capable of narrowing the resonance linewidth down to 0.1 Hz in a room-temperature atomic vapour cell. The potential of this technique for precision measurement is demonstrated through weak magnetic-field sensing. By judiciously pre- and post-selecting frequency-modulated input and output optical states in a nearly orthogonal manner, a sensitivity of 7 fT Hz -1/2 at a low frequency near DC is achieved using only one laser beam with 15 µW of power. Additionally, our results extend the WM framework to a non-Hermitian Hamiltonian and shed new light on metrology and bio-magnetic field sensing.

Science & Technology - Other Topics↗
NASA NTRS1978

Characteristics of integrated MOM junctions at dc and at optical frequencies

A new metal-oxide-metal device (Ni-NiO-Ni, Edge MOM) which is stable, reproducibly fabricated, and with a 10 to the -10th sq cm tunneling area is presented. Performing detection experiments, the device's nonlinear I-V characteristic is shown to be invariant at audio frequencies, 10.6, 3.39, and 0.6328 microns. Similar devices with 10 to the -8th sq cm tunneling areas perform as well as the Edge MOM's in the visible and the near-infrared range, but deteriorate in performance at the 10-micron range. A dominant competing effect is a thermal-induced signal, which increases with frequency and temperature. Coupling mechanisms at the various regimes are investigated. The device can serve as a broad-band detector and mixer, and might in the future be a basic element of broad-band amplifiers and oscillators.

Heiblum, M.↗