Dr. John Seamons Profile

Dr. John Seamons

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Publications (4)

Proceedings Article | 22 July 2010 Paper

Fringe modulation for an MROI beam combiner

T. McCracken, C. Jurgenson, D. Baird, J. Seamons, K. McCord, D. Buscher, C. Haniff, J. Young

Proceedings Volume 7734, 77343V (2010) https://doi.org/10.1117/12.857295

KEYWORDS: Modulators, Modulation, Field programmable gate arrays, Sensors, Control systems, Atmospheric corrections, Amplifiers, Detection and tracking algorithms, Optical tracking, Mirrors

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Proceedings Article | 22 July 2010 Paper

Assembly and integration activities moving toward commissioning of the Magdalena Ridge Observatory Interferometer

Eric Bakker, Andres Olivares, Fernando Santoro, Ifan Payne, Rob Selina, Dan Klinglesmith, Allen Farris, Ron King, Colby Jurgenson, John Seamons, Nicolas Torres, Michelle Creech-Eakman, Krista McCord

Proceedings Volume 7734, 77340V (2010) https://doi.org/10.1117/12.856468

KEYWORDS: Telescopes, Interferometers, Optical instrument design, Magdalena Ridge Observatory, Space telescopes, Mirrors, Observatories, Interferometry, Optics manufacturing, Computer aided design

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Proceedings Article | 19 July 2010 Paper

Software architecture of the Magdalena Ridge Observatory Interferometer

Allen Farris, Dan Klinglesmith, John Seamons, Nicolas Torres, David Buscher, John Young

Proceedings Volume 7740, 77400R (2010) https://doi.org/10.1117/12.856497

KEYWORDS: Databases, Telescopes, Control systems, Interferometers, Telecommunications, Java, Magdalena Ridge Observatory, Computing systems, Diagnostics, Distributed computing

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Proceedings Article | 3 April 2008 Paper

High bit rate germanium single photon detectors for 1310nm

J. Seamons, M. Carroll

Proceedings Volume 6976, 697607 (2008) https://doi.org/10.1117/12.778125

KEYWORDS: Germanium, Avalanche photodetectors, Single photon detectors, Sensors, Quantum efficiency, Near infrared, Temperature metrology, Single photon, Quantum key distribution, Avalanche photodiodes

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There is increasing interest in development of high speed, low noise and readily fieldable near infrared (NIR) single photon detectors. InGaAs/InP Avalanche photodiodes (APD) operated in Geiger mode (GM) are a leading choice for NIR due to their preeminence in optical networking. After-pulsing is, however, a primary challenge to operating InGaAs/InP single photon detectors at high frequencies1. After-pulsing is the effect of charge being released from traps that trigger false ("dark") counts. To overcome this problem, hold-off times between detection windows are used to allow the traps to discharge to suppress after-pulsing. The hold-off time represents, however, an upper limit on detection frequency that shows degradation beginning at frequencies of ~100 kHz in InGaAs/InP. Alternatively, germanium (Ge) single photon avalanche photodiodes (SPAD) have been reported to have more than an order of magnitude smaller charge trap densities than InGaAs/InP SPADs², which allowed them to be successfully operated with passive quenching² (i.e., no gated hold off times necessary), which is not possible with InGaAs/InP SPADs, indicating a much weaker dark count dependence on hold-off time consistent with fewer charge traps. Despite these encouraging results suggesting a possible higher operating frequency limit for Ge SPADs, little has been reported on Ge SPAD performance at high frequencies presumably because previous work with Ge SPADs has been discouraged by a strong demand to work at 1550 nm. NIR SPADs require cooling, which in the case of Ge SPADs dramatically reduces the quantum efficiency of the Ge at 1550 nm. Recently, however, advantages to working at 1310 nm have been suggested which combined with a need to increase quantum bit rates for quantum key distribution (QKD) motivates examination of Ge detectors performance at very high detection rates where InGaAs/InP does not perform as well. Presented in this paper are measurements of a commercially available Ge APD operated at relatively short GM hold-off times to examine whether there are potential advantages to using Ge for 1310 nm single photon detection. A weaker after-pulsing dependence on frequency is observed offering initial indications of the potential that Ge APDs might provide better high frequency performance.

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