Gabor F. Fulop

Time-encoded multiplexed imaging (Conference Presentation)

We describe a technique for multiplexed imaging that is based on the concept of mapping scene features to unique temporal codes, and using smart digital pixels to efficiently decode at the focal-plane. We use this technique to demonstrate multiplexed multispectral imaging using actively encoded LEDs, and multiplexed hyperspectral imaging using a digital micromiror spatial light modulator. Both experiments utilize a computational imaging array comprised of a 32x32 array of digital pixels with the capability of acquiring eight concurrent measurements that can be modulated with a time-varying duo-binary signal (+1,-1,0) at MHz rates. This results in eight decoded images per frame at a maximum frame rate of 1600 frames per second. The total frame rate of the imaging system depends on the number of encoded features and the number of decoding channels within the digital pixel. We explore these trades as well as discuss limitations and areas for future improvement.

VISTA video and overview (Conference Presentation)

The abstract is not available

Production manufacturing of 5" diameter gallium antimonide substrates (Conference Presentation)

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Large diameter Epi-ready GaSb substrate manufacturing (Conference Presentation)

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Implementing VISTA technology in a III-V detector foundry (Conference Presentation)

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8μm manufacturing for low-cost advanced Dewars(Conference Presentation)

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Multi-wafer production MBE capabilities for Sb-based type-II SLS IR detectors (Conference Presentation)

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SLS-based camera development at FLIR systems (Conference Presentation)

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III-V strained layer superlattice infrared detector characteristics and FPA performance (Conference Presentation)

The abstract is not available

A comparative study of carrier lifetimes in ESWIR and MWIR materials: HgCdTe, InGaAs, InAsSb, and GeSn (Conference Presentation)

HgCdTe has been the material of choice for MWIR, and LWIR infrared sensing due to its highly tunable band gap and favorable material properties. However, HgCdTe growth and processing for the ESWIR spectral region is less developed, so alternative materials are actively researched. It is important to compare the fundamental limitations of each material to determine which offers optimal device performance. In this article, we investigate the intrinsic recombination mechanisms of ESWIR materials—InGaAs, GeSn, and HgCdTe—with cutoff wavelength near 2.5μm, and MWIR with cutoff of 5μm. First, using an empirical pseudo-potential model, we calculate the full band structure of each alloy using the virtual crystal approximation, modified to include disorder effects and spin-orbit coupling. We then evaluate the Auger and radiative recombination rates using a Green’s function based model, applied to the full material band structure, yielding intrinsic carrier lifetimes for each given temperature, carrier injection, doping density, and cutoff wavelength. For example, we show that ESWIR HgCdTe has longer carrier lifetimes than InGaAs when strained or relaxed near room temperature, which is advantageous for high operating temperature photodetectors. We perform similar analyses for varying composition GeSn by comparing the calculated lifetimes with InGaAs and HgCdTe. Finally, we compare HgCdTe, InAsSb and GeSn with a cutoff in the MWIR spectral band.