Publications
Analog coupled oscillator based weighted Ising machine
Summary
Summary
We report on an analog computing system with coupled non-linear oscillators which is capable of solving complex combinatorial optimization problems using the weighted Ising model. The circuit is composed of a fully-connected 4-node LC oscillator network with low-cost electronic components and compatible with traditional integrated circuit technologies. We present the...
Key Challenges and Prospects for Optical Standoff Trace Detection of Explosives
Summary
Summary
Sophisticated improvised explosive devices (IEDs) challenge the capabilities of current sensors, particularly in areas away from static checkpoints. This security gap could be filled by standoff chemical sensors that detect IEDs based on external trace explosive residues. Unfortunately, previous efforts have not led to widely deployed capabilities. Crucially, the physical...
Spatially-resolved individual particle spectroscopy using photothermal modulation of Mie scattering
Summary
Summary
We report a photothermal modulation of Mie scattering (PMMS) method that enables concurrent spatial and spectral discrimination of individual micron-sized particles. This approach provides a direct measurement of the "fingerprint" infrared absorption spectrum with the spatial resolution of visible light. Trace quantities (tens of picograms) of material were deposited onto...
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...
Coherent beam-combining of quantum cascade amplifier arrays
Summary
Summary
We present design, packaging and coherent beam combining of quantum cascade amplifier (QCA) arrays, measurements of QCA phase noise, the drive-current-to-optical-phase transfer function, and the small signal gain for QCAs.
Advanced trigger development
Summary
Summary
The deadliest form of a biological attack is aerosolized agents dispersed into the atmosphere. Early detection of aerosolized biological agents is important for defense against these agents. Because of the wide range of possible attack scenarios and attack responses, there is also a wide range of detector requirements. This article...
Measurement of aerosol-particle trajectories using a structured laser beam
Summary
Summary
What is believed to be a new concept for the measurement of micrometer-sized particle trajectories in an inlet air stream is introduced. The technique uses a light source and a mask to generate a spatial pattern of light within a volume in space. Particles traverse the illumination volume and elastically...