10.1117/2.1201007.003077
IR detectors for spaceborne laser
receivers
Michael Krainak, Xiaoli Sun, and Guangning Yang
High-speed optical detectors that are sensitive in the near-IR wavelength region have application in global 3D mapping, atmospheric gas
measurements, and laser communications.
NASA conducts science investigations using spaceborne instruments on custom-built satellite platforms. The instruments
enable global measurements of the Earth, moon, and planets,
as well as investigations of astrophysical science. The satellites
require communication and navigation systems. Accordingly,
continuing advances in laser technology facilitate new satellite infrastructure. Our engineering goal is to make the highestquality science product for the lowest cost (i.e., to minimize size,
weight, and power). For laser-based systems this means using
the highest electrical input to optical output efficiency lasers
with the most sensitive near-IR detectors. We emphasize the
near-IR regime because a combination of economics and materials science has enabled the most science-applicable, efficient,
and reliable lasers at these wavelengths. However, devices still
require improvements for high speed and sensitivity to qualify
for space operation.
Both laser-based time-of-flight instruments (e.g., laser range
systems and altimeters) and high-bandwidth laser-communication terminals have increased capability by employing short
pulses (<1ns) and optimizing the laser receiver signal-to-noise
ratio (SNR). Ideally, a laser receiver detector can detect a single
photon, thus attaining near-ultimate receiver sensitivity. Some of
NASA’s laser-ranging and altimetry instruments have improved
the system performance (including SNR) by frequency doubling
the laser to allow use of single-photon-sensitive detectors—
e.g., silicon avalanche photodiodes (APDs)1 or photomultiplier
tubes—at visible (green) wavelengths. This is suboptimal,
because it provides only half of the total number of photons per
Watt. Moreover, losses are associated with the practical implementation of efficient frequency doubling at high power. Since
1990, all of NASA’s space-based laser-altimetry missions have
used versions of the near-IR-enhanced silicon APD detector
manufactured by PerkinElmer Opto-Electronics Canada for use
Figure 1. Near-IR detectors. (a) Impact-ionization-engineered indium
aluminum arsenide avalanche photodiode (APD). (b) Mercury cadmium telluride APD on dewar. (c) Hybrid photomultiplier tube.
at 1064nm wavelength. The silicon band gap reduces absorption
in the near-IR range, necessitating a thick absorption region.
Unfortunately, this also increases the dark-current noise (i.e.,
electrical signals not caused by light), thus limiting the sensitivity. As a result, new materials and approaches are required to
achieve single-photon sensitivity in the near-IR spectral range.
NASA’s first such effort (the Lunar Laser Communication
Demonstration, being designed and built at the Massachusetts
Institute of Technology’s Lincoln Laboratory for launch in
March 2013) will use a 1.5m-wavelength single-mode fiber preamplifier receiver with an indium gallium arsenide (InGaAs)
p-i-n diode detector on the lunar orbiting spaceborne terminal.
Performance is expected to be tens of photons per bit sensitivity.
For all of NASA’s spaceborne near-IR laser receiver applications, our goal is to achieve single-photon sensitivity. We
are investigating InGaAs, indium aluminum arsenide (InAlAs),
InGaAs phosphide (InGaAsP), mercury cadmium telluride
(HgCdTe), and resonant-cavity-enhanced silicon APDs, as well
as InGaAs or InGaAsP photocathode photomultiplier tubes
(see Figure 1).
None of the linear-mode APDs we have tested from numerous companies have been able to match the performance
of the PerkinElmer silicon APD. We have achieved improved
Continued on next page
10.1117/2.1201007.003077 Page 2/2
performance (and 1GHz electrical bandwidth) by developing
an impact-ionization-engineered InAlAs APD. InGaAs Geigermode APDs can achieve single-photon detection but have
recently been shown to be susceptible to space-radiation
damage, which limits their applicability to multiyear NASA
missions. We continue to develop HgCdTe APDs in collaboration with US industry. Recent results include >100MHz electrical bandwidth, tens-of-photons sensitivity, and low excess-noise
factor (1.1). This challenges our gold-standard silicon APD. Recent international results2 indicate that numerous improvements
are still achievable.
We have measured good performance from custom-selected
dynode-chain (a set of metal plates inside the photomultiplier
tube that provide gain at each plate) InGaAs photocathode photomultiplier tubes. These include >10% single-photon detection
efficiency at 1550nm, near-GHz bandwidth, large area (1mm),
low excess-noise factor (1.2), and reasonable dark-count rates
(electrical noise in pulses per second) (<1Mcps). We achieved
the best performance from InGaAsP photocathode hybrid photomultiplier tubes.3 We measured 25% single-photon detection
efficiency at a wavelength of 1064nm with a dark-count rate
of 60,000/s at 22ı C. The single-photon response-output pulse
width is 0.9ns with a timing jitter of 500ps. The maximum count
rate exceeds 100Mcps. In summary, a new generation of highsensitivity near-IR detectors for spaceborne laser instruments
will enable new science, including high-precision global
measurements of the Earth’s and planetary topography, and
atmospheric trace gases (e.g., carbon dioxide and methane). In
addition, high-sensitivity near-IR detectors should make possible new spacecraft infrastructure with laser communications and
navigation. NASA continues to invest in improved APD and
photomultiplier technology for these efforts.
Author Information
Michael Krainak, Xiaoli Sun, and Guangning Yang
NASA Goddard Space Flight Center
Greenbelt, MD
Michael Krainak received his PhD in electrical engineering from
Johns Hopkins University. He has worked at AT&T Western
Electric, the Defense Department, and Quantum Photonics. For
19 years he has worked on laser instruments at NASA Goddard
Space Flight Center, where he heads the Laser and Electro-Optics
Branch.
References
1. X. Sun et al., Space-qualified silicon avalanche-photodiode single-photon-counting modules, J. Mod. Opt. 51 (9–10), pp. 1333–1350, 2004.
2. G. Perrais et al., Study of the transit-time limitations of the impulse response in midwave infrared HgCdTe avalanche photodiodes, J. Electron. Mater. 38 (8), pp. 1790–1799,
2009.
3. X. Sun et al., Single-photon counting at 950 to 1300nm: using InGaAsP photocathodeGaAs avalanche diode hybrid photomultiplier tubes, J. Mod. Opt. 56, pp. 284–295, 2009.
c 2010 SPIE