Modification and Identification of the Beam Waveguide Antenna Control System Model
This work is the first step toward increasing the bandwidth of the NASA/JPL 34 meter beam waveguide (BWG) antenna position loop controller.
Beam Waveguide Antenna↗
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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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A New Technique for Vernier Pointing of a Beam-Waveguide Antenna
This paper presents a new and simple approach for the Ka-band vernier pointing of a 34m beam-waveguide (BWG) antenna (also applicable to a 70m antenna. In this study, rotation of a BWG flat mirror, located at the elevation axis, is used to scan the beam instead of using the very large tipping structure of the antenna.
antenna pointing vernier pointing beam-waveguide K↗
Frequency Tripler with Integrated Back-to-Back Barrier -N-N(sup +) (bbBNN) Varactor Diodes in a Novel Split-Waveguide Block at 220 GHz
A frequency tripler has been developed using an integrated planar back-to-back -n-n(sup +) varactor device in a waveguide mount at 220 GHz.
frequency tripler split-waveguide block design int↗
Characteristics of the Single-Longitudinal-Mode Planar-Waveguide External Cavity Diode Laser at 1064 nm
We describe the characteristics of the planar-waveguide external cavity diode laser (PW-ECL). To the best of our knowledge, it is the first butterfly-packaged 1064 nm semiconductor laser that is stable enough to be locked to an external frequency reference. We evaluated its performance from the viewpoint of precision experiments. Using a hyperfine absorption line of iodine, we suppressed its frequency noise by a factor of up to 104 at 10 mHz. The PWECL's compactness and low cost make it a candidate to replace traditional Nd:YAG nonplanar ring oscillators and fiber lasers in applications that require a single longitudinal mode.
planar-waveguide↗
Free-Space Quantum Key Distribution with a High Generation Rate KTP Waveguide Photon-Pair Source
NASA awarded Small Business Innovative Research (SBIR) contracts to AdvR, Inc to develop a high generation rate source of entangled photons that could be used to explore quantum key distribution (QKD) protocols. The final product, a photon pair source using a dual-element periodically- poled potassium titanyl phosphate (KTP) waveguide, was delivered to NASA Glenn Research Center in June of 2015. This paper describes the source, its characterization, and its performance in a B92 (Bennett, 1992) protocol QKD experiment.
photons↗
Waveguide Modulator for Interference Tolerant Functional Near Infrared Spectrometer (fNIRS)
Many crew-related errors in aviation and astronautics are caused by hazardous cognitive states including overstress, disengagement, high fatigue and ineffective crew coordination. Safety can be improved by monitoring and predicting these cognitive states in a non-intrusive manner and designing mitigation strategies. Measuring hemoglobin concentration changes in the brain with functional Near Infrared Spectroscopy is a promising technique for monitoring cognitive state and optimizing human performance during both space and aviation operations. A compact, wearable fNIRS system would provide an innovative early warning system during long duration missions to detect and prevent vigilance decrements in pilots and astronauts. This effort focused on developing a waveguide modulator for use in a fNIRS system.
spectroscopy↗
InP-Based Ridge Waveguide Lasers for Wavelength Division Multiplexing Applications
Wavelength division multiplexed (WDM) systems place stringent requirements on the absolute wavelength and wavelength spacing of the elements in laser arrays. Ridge waveguides (RW) show excellent potential for practical implementation due to their simple fabrication with relaxed fabrication tolerances, high reliability and good performancce. An analysis of the fabrication tolerances for RW and buried heterostructure (BH) devices is performed, showing the advantages offered by the ridge design.
wavelength↗
A Novel Noncontacting Waveguide Backshort for Submillimeter Wave Frequencies
A novel noncontacting waveguide backshort has been developed which provides excellent performance. It consists of a metallic bar with rectangular or circular holes. It has the advantage of being mechanically rugged and readily fabricated using a variety of methods for frequencies up to the high submillimeter wave range.
waveguide↗
Design Techniques for Beam Waveguide Systems
Various design techniques used for beam waveguide (BWG) feed systems are characterized. These include the use of gaussian beam, geometrical optics, and physical optics systems. Also introduced is a new technique based upon a conjugate phase matching focal plane technique. Advantages, disadvantages, and range of applicability of each technique is given, In addition, comparisons of computed and measured results from each type of design are presented.
beam↗
A Novel Design Technique for Beam-Waveguide Antennas
The new 34-m beam-waveguide (BWG) antenna at Goldstone has a beam magnifier ellipse below ground level that transforms a 22-dB gain feedhorn into a high-gain 29-dB gain pattern for input to a standard four-mirror BWG system. It was initially designed for the X- an Ka-bands, and has a loss of less than 0.2 dB.
antenna↗
The Electrical Conductivities of Candidate Beam-Waveguide Antenna Shroud Materials
The shroud on a new NASA/JPL beam-waveguide (BWG) antenna is made from highly magnetic American Society for Testing and Materials (ASTM) A36 steel. Measurements at 8.42 GHz showed that this material (with paint) has a very poor electrical conductivity that is 600 times worse than aluminum.
Electrical↗
A Novel Design Technique for Beam-Waveguide Antennas
Paper covers the poor low-frequency performance of geometrically designed beam-waveguide antennas,and a novel design technique for solving this poor performance. A unique application was made of the conjugate phase-matching techniques to obtain the desired solution.
beam-waveguide↗
Tailorable Optical Response of Au-LiNbO 3 Hybrid Metamaterial Thin Films for Optical Waveguide Applications
Photonic integrated circuits require various optical materials with versatile optical properties and easy on–chip device integration. To address such needs, a well–designed nanoscale metal–oxide metamaterial, that is, plasmonic Au nanoparticles embedded in nonlinear LiNbO 3 (LNO) matrix, is demonstrated with tailorable optical response. Specifically, epitaxial and single–domain LNO thin films with tailored Au nanoparticle morphologies (i.e., various nanoparticle sizes and densities), are grown by a pulsed laser deposition method. The optical measurement presents obvious surface plasmon resonance and dramatically varied complex dielectric function because of the embedded Au nanoparticles, and its response can be well tailored by varying the size and density of Au nanoparticles. An optical waveguide structure based on the thin film stacks of a–Si on SiO 2 /Au–LNO is fabricated and exhibits low optical dispersion with an optimized evanescent field staying in the LNO–Au active layer. Furthermore, the hybrid Au–LNO metamaterial thin films provide a novel platform for tunable optical materials and their future on–chip integrations in photonic–based integrated circuits.
36 MATERIALS SCIENCE↗
Extracting interface locations in multilayer polymer waveguide films using scanning angle Raman spectroscopy
There is an increasing demand for nondestructive in situ techniques that measure chemical content, total thickness, and interface locations for multilayer polymer films, and SA Raman spectroscopy in combination with appropriate data models can provide this information. A scanning angle (SA) Raman spectroscopy method was developed to measure the chemical composition of multilayer polymer waveguide films and to extract the location of buried interfaces between polymer layers with 7–80-nm axial spatial resolution. The SA Raman method measures Raman spectra as the incident angle of light upon a prism-coupled thin film is scanned. Six multilayer films consisting of poly(methyl methacrylate)/polystyrene or poly(methyl methacrylate)/polystyrene/poly(methyl methacrylate) were prepared with total thicknesses ranging from 330-1260 nm. The interface locations were varied by altering the individual layer thicknesses between 140-680 nm. The Raman amplitude ratio of the 1605 cm -1 peak for PS and 812 cm -1 peak for PMMA was used in calculations of the electric field intensity within the polymer layers to model the SA Raman data and extract the total thickness and interface locations. There is an average 8% and 7% difference in the measured thickness between the SA Raman and profilometry measurements for bilayer and trilayer films, respectively.
36 MATERIALS SCIENCE↗
Ultrafast Waveguiding Quantum Dot Scintillation Detector
Picosecond timing of energetic charged particles and photons is a challenge for many high-energy physics and medical applications. InAs Quantum Dots (QDs) embedded in GaAs matrix are expected to have unsurpassed scintillation properties. The advantages come from highly efficient energy conversion, as well as from fast electron capture and radiative recombination in QDs. Here, we present design considerations and demonstration of an ultrafast, high photon yield room-temperature semiconductor scintillator. Due to the high refractive index of GaAs, the scintillator is fabricated in the form of a20 μm thick planar waveguide with an integrated InGaAs photodiode. QD luminescence of about 60% efficiency at room temperature has been shown, and modal attenuation stabilized at 1 cm -1 . Scintillation responses from 5.5 MeV alpha particles show an extremely fast decay time of 280 ps, a collection efficiency of 11% and a time resolution of 60 ps. This data confirms the unique potential properties of this scintillation detector.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Experimental design of a W-band corrugated waveguide for wakefield acceleration studies
Radiofrequency (RF) structures in the sub-terahertz (sub-THz) regime are of interest for applications in structure wakefield acceleration due to their compact size and potential for high gradients. Here, we present the design, fabrication, and experimental setup of a metallic corrugated waveguide at 110 GHz, optimized for the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The emittance exchange (EEX) beamline at AWA was used to perform longitudinal bunch shaping for two cases: (1) a high decelerating gradient experienced by a single drive electron bunch about 250 μm long; (2) a high transformer ratio using a two-bunch train consisting of a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield. Preliminary experimental results are presented, and data analysis is ongoing.
43 PARTICLE ACCELERATORS↗
Extraction and selective promotion of zero-group velocity and cutoff frequency resonances in bi-dimensional waveguides using the electromechanical impedance method
This study showcases the electromechanical impedance (EMI) technique for extracting and promoting zero-group velocity (ZGV) and cutoff frequency resonances in a waveguide structure. Here, we identify the mechanisms of multiple resonances in the EMI spectra via a wave propagation perspective. Both simulation and experiments reveal the fact that sharp resonances in the conductance spectra are associated with either ZGV or cutoff frequency points. Consequently, we design four test configurations to enhance local resonances by aligning induced motions with considered mode shapes. Reasonable agreement between simulation and experiment results is observed. We evaluate the performance of considered configurations in terms of mode enhancement, and configurations that can selectively promote certain mode families are summarized. This study also shines the light on the EMI technique for quantitative non-destructive evaluation (NDE) by potentially supporting the inverse characterization of mechanical properties of host structures.
42 ENGINEERING↗
Optical Waveguiding Charge-Transfer Cocrystals: Examining the Impact of Molecular Rotations on Their Photoluminescence
Here, we present the first example of a binary optical waveguiding (OWG) cocrystal with large anisotropy featuring a fluorinated acceptor molecule (CPP-TFPN, 1) with on-plane rotational dynamics, confirmed by solid-state NMR ( 19 F T 1 ) and theoretical calculations. Spatially resolved microphotoluminescence and variable-temperature photoluminescence experiments allowed us to examine the OWG performance and photophysical properties of both single crystals and bulk microcrystalline samples. A comparison with an analogous cocrystal containing a regioisomeric acceptor (CPP-TFTN, 2) revealed that the photoluminescence characteristics of 1 are associated with the rotational motions of the acceptor, offering insights into how the molecular motion changes this property.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗