There are a number of potential non-NASA commercial applications that will benefit from the development of NFAD arrays. Range-finding and ladar applications present many commercial opportunities (e.g., terrain/vegetation mapping, flood/landslide risk mapping, civil engineering projects, etc.) in which the availability of single photon sensitivity could be a disruptive improvement over existing optical remote sensing technologies. Just as NASA is pursuing free space optical links, commercial FSO systems will be able to leverage capabilities realized from the development of NFAD arrays for photon-starved free space links, particularly in cases for which pointing and tracking are required, such as in satellite communications. As with NASA remote sensing applications, there are commercial applications for NFADs in various types of lidar systems for measuring atmospheric properties such as wind and weather patterns, air pollution, and general trace gas analysis. Finally, high-performance photon counting capability in the near- and shortwave-infrared is desirable for the detection of low light output fluorescence, photoluminescence and photoemission processes, particularly for biomedical applications. There are two primary NASA applications for the negative feedback avalanche diode (NFADs) arrays to be developed during this proposed SBIR program. First, free space optical (laser) communications over interplanetary distances epitomizes photon-starved applications, and viable spacecraft receiver technologies should have high-performance single photon detection to enable coding schemes such as pulse position modulation while imposing minimal size, weight, and power requirements. The need for simultaneous pointing and tracking is a driver for array-based detector solutions. Second, active remote sensing optical instruments require higher performance photon detectors to improve the performance of existing direct detection lidar systems used to perform atmospheric measurements (e.g., aerosol backscattering) and surface mapping (e.g., ice sheets and forest canopy density).