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Proceedings Paper

Advanced silicon avalanche photodiodes on NASA's Global Ecosystem Dynamics Investigation (GEDI) mission
Author(s): Xiaoli Sun; J. Bryan Blair; Jack L. Bufton; Marcela Faina; Sigrid Dahl; Philippe Bérard; Richard J. Seymour
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Paper Abstract

Silicon Avalanche Photodiodes (APDs) are used in NASA’s Global Ecosystem Dynamics Investigation (GEDI) that was launched in December 2018 and is currently measuring the Earth’s vegetation vertical structure from the International Space Station. The APDs were specially made for space lidar with a much lower hole-to-electron ionization coefficient ratio (k-factor ~0.008) than that of commercially available silicon APDs in order to reduce the APD excess noise. A silicon heater resistor was used under the APD chip to heat the device to 70°C to improve its quantum efficiency at the 1064-nm laser wavelength while maintaining a low dark current such that the overall signal to noise ratio is optimized. Special APD protection circuits were included to raise the overload damage threshold to prevent device damage from strong laser returns from specular surfaces, such as still water bodies, and space radiation events. The APD and a hybrid transimpedance amplifier circuit were hermetically sealed in a TO-8 type metal package with a sufficiently low leak rate to ensure a multi-year operation lifetime in space. The detector assemblies underwent a series of pre-launch tests per NASA Goddard Environmental Verification Standard for space qualification. The APDs have performed exactly as expected in space. A detailed description of the GEDI detector design, signal and test results are presented in this paper.

Paper Details

Date Published: 2 March 2020
PDF: 11 pages
Proc. SPIE 11287, Photonic Instrumentation Engineering VII, 1128713 (2 March 2020); doi: 10.1117/12.2545203
Show Author Affiliations
Xiaoli Sun, NASA Goddard Space Flight Ctr. (United States)
J. Bryan Blair, NASA Goddard Space Flight Ctr. (United States)
Jack L. Bufton, Global Science & Technology, Inc. (United States)
Marcela Faina, Excelitas Canada, Inc. (Canada)
Sigrid Dahl, Excelitas Canada, Inc. (Canada)
Philippe Bérard, Excelitas Canada, Inc. (Canada)
Richard J. Seymour, Excelitas Canada, Inc. (Canada)

Published in SPIE Proceedings Vol. 11287:
Photonic Instrumentation Engineering VII
Yakov Soskind; Lynda E. Busse, Editor(s)

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