William H. Farr

Jet Propulsion Laboratory

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Matthew D. Shaw

Jet Propulsion Laboratory

Kevin Birnbaum

Meta (United States)

Abhijit Biswas

Jet Propulsion Laboratory

Hamid Hemmati

Semnan University of Medical Sciences

Francesco Marsili

Jet Propulsion Laboratory

Richard P. Mirin

National Institute of Standards and Technology

Varun B. Verma

National Institute of Standards and Technology

Sae Woo Nam

National Institute of Standards and Technology

Jeffrey A. Stern

New York University

Kevin J. Quirk

Meta (United States)

Cooperative Institutions

Jet Propulsion Laboratory

111

California Institute of Technology

National Institute of Standards and Technology

Massachusetts Institute of Technology

National Institute of Standards

University of Illinois Urbana-Champaign

University of Colorado Boulder

Lancaster University

University of Maryland, College Park

Meta (United States)

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Electro-Optic Time-to-Space Converter for Optical Detector Jitter Mitigation

Kevin Birnbaum William H. Farr

A common problem in optical detection is determining the arrival time of a weak optical pulse that may comprise only one to a few photons. Currently, this problem is solved by using a photodetector to convert the optical signal to an electronic signal. The timing of the electrical signal is used to infer the timing of the optical pulse, but error is introduced by random delay between the absorption of the optical pulse and the creation of the electrical one. To eliminate this error, a time-to-space converter separates a sequence of optical pulses and sends them to different photodetectors, depending on their arrival time. The random delay, called jitter, is at least 20 picoseconds for the best detectors capable of detecting the weakest optical pulses, a single photon, and can be as great as 500 picoseconds. This limits the resolution with which the timing of the optical pulse can be measured. The time-to-space converter overcomes this limitation. Generally, the time-to-space converter imparts a time-dependent momentum shift to the incoming optical pulses, followed by an optical system that separates photons of different momenta. As an example, an electro-optic phase modulator can be used to apply longitudinal momentum changes (frequency changes) that vary in time, followed by an optical spectrometer (such as a diffraction grating), which separates photons with different momenta into different paths and directs them to impinge upon an array of photodetectors. The pulse arrival time is then inferred by measuring which photodetector receives the pulse. The use of a time-to-space converter mitigates detector jitter and improves the resolution with which the timing of an optical pulse is determined. Also, the application of the converter enables the demodulation of a pulse position modulated signal (PPM) at higher bandwidths than using previous photodetector technology. This allows the creation of a receiver for a communication system with high bandwidth and high bits/photon efficiency.

Picosecond

SIGNAL (programming language)

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Technology development for high efficiency optical communications

IEEE Aerospace Conference (2012)

William H. Farr

Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

Transceiver

Deep space exploration

Free-Space Optical Communication

space technology

Communications satellite

10.1109/aero.2012.6187270

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Palomar Receive Terminal (PRT) for the Mars Laser Communication Demonstration (MLCD) Project

Proceedings of the IEEE (2007)

Abhijit Biswas Bruce Moision W. T. Roberts William H. Farr A. D. Gray

Significant technological advances were made toward utilizing the Hale telescope for receiving the faint laser communication signals transmitted from an optical transceiver on a spacecraft orbiting Mars. The so-called Palomar receive terminal design, which would have supported nominal downlink data rates of 1-30 Mbps, is described. Testing to validate technologies for near-Sun (3deg from edge of solar disc) daytime operations is also discussed. Finally, a laboratory end-to-end link utilizing a 64-ary pulse-position modulated photon-counting receiver and decoder that achieved predicted near-capacity (within 1.4 dB) performance is described.

Transceiver

Free-Space Optical Communication

Pulse-position modulation

Data link

10.1109/jproc.2007.905054

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Photon Counting Arrays for Deep Space Optical Beacon Acquisition and Tracking

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2011)

William H. Farr Meera Srinivasan Ferze D. Patawaran Kevin J. Quirk Danh H. Nguyen

Photon Counting

Tracking (education)

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Proton irradiation of InGaAs/InP and InGaAsP/InP Geiger-mode avalanche photodiodes

European Conference on Radiation and Its Effects on Components and Systems (2009)

R.D. Harris William H. Farr Heidi N. Becker

Degradation of InGaAs/InP and InGaAsP/InP Geiger-mode avalanche photodiodes caused by proton irradiation is studied for the first time. Substantial changes in the dark I-V characteristics as well as increases in the dark count rate are observed after irradiation. There are no systematic changes in photon count rate observed or in the amount of after-pulsing. The devices are rendered non-operational following a fluence of 8.1×10 ¹⁰ 50-Mev protons/cm ² for room temperature operation.

Photodiode

Geiger counter

Photon Counting

Indium gallium arsenide

10.1109/radecs.2009.5994684

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A systematic and comprehensive tool for software reliability modeling and measurement

Michael R. Lyu Allen P. Nikora William H. Farr

Sufficient work has been done to demonstrate that software reliability models can be used to monitor reliability growth over a useful range of software development projects. However, due to the lack of appropriate tools, the application of software reliability models as a means for project management is not as widespread as it might be. The existing software reliability modeling and measurement programs are either difficult for a nonspecialist to use, or short of a systematic and comprehensive capability in the software reliability measurement practice. To address the ease-of-use and the capability issues, the authors have prototyped a software reliability modeling tool called CASRE, a Computer-Aided Software Reliability Estimation tool. Implemented with a systematic and comprehensive procedure as its framework, CASRE will encourage more widespread use of software reliability modeling and measurement as a routine practice for software project management. The authors explore the CASRE tool to demonstrate its functionality and capability.

Software reliability testing

Software sizing

Software metric

Software project management

Software measurement

10.1109/ftcs.1993.627369

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Citations (13)

Index

BRILL eBooks (1974)

William H. Farr

10.1163/9789004476974_015

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Photon counting detector array algorithms for deep space optical communications

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2016)

Meera Srinivasan K. Andrews William H. Farr Andre Wong

For deep-space optical communications systems utilizing an uplink optical beacon, a single-photon-counting detector array on the flight terminal can be used to simultaneously perform uplink tracking and communications as well as accurate downlink pointing at photon-starved (pW=m²) power levels. In this paper, we discuss concepts and algorithms for uplink signal acquisition, tracking, and parameter estimation using a photon-counting camera. Statistical models of detector output data and signal processing algorithms are presented, incorporating realistic effects such as Earth background and detector/readout blocking. Analysis and simulation results are validated against measured laboratory data using state-of-the-art commercial photon-counting detector arrays, demonstrating sub-microradian tracking errors under channel conditions representative of deep space optical links.

Photon Counting

SIGNAL (programming language)

Tracking (education)

10.1117/12.2217971

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Citations (29)

Deep space acquisition and tracking with single photon detector arrays

William H. Farr Suzana Sburlan Adit Sahasrabudhe Kevin Birnbaum

The laser beacon power required by a communication terminal for acquisition and tracking in deep space optical link scenarios can be reduced by a factor of 10 to 100 by replacing an integrating array, such as a CCD, with an array of single photon detectors. An additional benefit of the single photon detector array is that each pixel can have MHz bandwidths, allowing simultaneous recovery of photon time-of-arrival information that can be used for uplink data recovery or range measurements.

Tracking (education)

Free-Space Optical Communication

10.1109/icsos.2011.5783654

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Citations (12)

Degradation of InP-based Geiger-mode avalanche photodiodes due to proton irradiation

Journal of Modern Optics (2010)

R.D. Harris William H. Farr Heidi N. Becker

Abstract Degradation of InGaAs/InP Geiger-mode avalanche photodiodes caused by proton irradiation is reported for the first time. The devices are found to be very sensitive to displacement damage. Substantial changes in the dark count rate, and the after-pulse count rate are observed following room temperature irradiation and characterization at −50°C. The device detection efficiency is unaffected by irradiation. Following 51 MeV proton fluences in the mid 109 protons/cm2 range, the dark count rate becomes so large that the devices are rendered essentially unusable. This is a very low fluence at which to observe device failure. Keywords: APDavalanche photodiodeGeiger-modeproton irradiationradiation effectssingle photon detector Acknowledgements This research work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). Helpful discussions with Larry Edmonds and Steve Guertin at JPL on the histogram analysis are gratefully acknowledged.

Geiger counter

Photodiode

Jet propulsion

10.1080/09500340.2010.525328

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Citations (5)