We are developing near-IR photon-counting detectors for the CO2 sounders on ASCENDS and for multi- beam swath mapping laser altimeters for the Lidar Surface Topography (LIST) mission, both of which were recommended by the Earth Science Decadal Survey.

Our objectives are to improve the receiver sensitivity to the quantum limit, reduce the demand for the laser transmitter power and energy, and reduce mission costs. To accomplish this, we are developing high-quantum-efficiency photon-sensitive detectors for three wavelength regimes: near 1060 nm for next-generation laser altimeters, 1550-1650 nm for the CO2 sounder, and 3100-3400 nm for planetary methane sounders. We work closely with engineering personnel in the Lasers and Electro-Optics Branch (Code 554) and the Imaging Detector Branch (Code 553) to leverage the resources at GSFC.

Previously, this team provided the Si avalanche photodiode (APD) single-photon-counting modules for visible wavelengths and the near-IR enhanced- linear-mode Si APDs for the GLAS instrument on the ICESat mission. Now, we are conducting studies of various near-IR single photon-counting detectors on the market as well as all of the viable ones that have come from R&D efforts by industry and by research institutions with support from NASA's Small Business Innovative Research (SBIR) program, Department of Defense funding, and industry's own internal investments.
In addition, we have developed a lidar test bed to evaluate detector performance under simulated lidar signals, not only to demonstrate the detector performance but also to validate new measurement techniques enabled by the emerging new detectors. Three primary types of detectors being considered are: HgCdTe photodiodes, InGaAs single- photon avalanche diodes (SPADs), and InGaAs/InP photocathode photomultiplier tubes (PMTs).