Publications
Photonic lantern adaptive spatial mode control in LMA fiber amplifiers
Summary
Summary
We demonstrate adaptive-spatial mode control (ASMC) in few-moded double-clad large mode area (LMA) fiber amplifiers by using an all-fiber-based photonic lantern. Three single-mode fiber inputs are used to adaptively inject the appropriate superposition of input modes in a multimode gain fiber to achieve the desired mode at the output. By...
Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400-1400 cm-1
Summary
Summary
Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact ( 2'x2'x2'), sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these...
Comb generator design for SWaP-constrained applications
Summary
Summary
Many wireless devices have requirements that emphasize low size, weight and power for increased functionality and extended lifetimes. The additional complexity of these devices mandates the need to dynamically verify that all sub-system functions are fully operational. These tests can only be performed internal to the unit, and a circuit...
Simultaneous Transmit and Receive (STAR) mobile testbed
Summary
Summary
Simultaneous Transmit and Receive (STAR) systems typically utilize multiple cancellation layers to improve system isolation and avoid self-interference. The design of these different layers must be evaluated both individually and as a whole to determine their effectiveness in various environments. A flexible and reusable mobile testbed was constructed to aid...
Reagent approaches for improved detection of chlorate and perchlorate salts via thermal desorption and ionization
Summary
Summary
RATIONALE: Techniques for improving the detectability of chlorate and perchlorate salts with thermal desorption based ionizers (i.e. radioactive, corona discharge and photoionization-based) are desired. This work employs acidic reagents to chemically transform chlorate and perchlorate anions into traces of chloric and perchloric acid. These high vapor pressure acids are easier...
Photothermal speckle modulation for noncontact materials characterization
Summary
Summary
We have developed a noncontact, photothermal materials characterization method based on visible-light speckle imaging. This technique is applied to remotely measure the infrared absorption spectra of materials and to discriminate materials based on their thermal conductivities. A wavelength-tunable (7.5-8.7 um), intensity-modulated, quantum cascade pump laser and a continuous-wave 532 nm...
The evolution to modern phased array architectures
Summary
Summary
Phased array technology has been evolving steadily with advances in solid-state microwave integrated circuits, analysis and design tools, and reliable fabrication practices. With significant government investments, the technologies have matured to a point where phased arrays are widely used in military systems. Next-generation phased arrays will employ high levels of...
Enhancing the far-ultraviolet sensitivity of silicon complementary metal oxide semiconductor imaging arrays
Summary
Summary
We report our progress toward optimizing backside-illuminated silicon P-type intrinsic N-type complementary metal oxide semiconductor devices developed by Teledyne Imaging Sensors (TIS) for far-ultraviolet (UV) planetary science applications. This project was motivated by initial measurements at Southwest Research Institute of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures...
Secure architecture for embedded systems
Summary
Summary
Devices connected to the internet are increasingly the targets of deliberate and sophisticated attacks. Embedded system engineers tend to focus on well-defined functional capabilities rather than "obscure" security and resilience. However, "after-the-fact" system hardening could be prohibitively expensive or even impossible. The co-design of security and resilience with functionality has...
A near-quantum-limited Josephson traveling-wave parametric amplifier
Summary
Summary
Detecting single photon level signals--carriers of both classical and quantum information--is particularly challenging for low-energy microwave frequency excitations. Here we introduce a superconducting amplifier based on a Josephson junction transmission line. Unlike current standing-wave parametric amplifiers, this traveling wave architecture robustly achieves high gain over a bandwidth of several gigahertz...