Ultra scaling of SPAD arrays for high-speed laser ranging

Ultrasensitive detection of visible light has a wide range of applications, including laser ranging and free space optical communications. Ultimate sensitivity is achieved when individual return photons are counted with high probabilities of detection, low probabilities of false detection, and precision timing. Previously, high bandwidth was only achieved with PIN photodiode and avalanche photodiodes, with detection limits of 1000 and 100 photons respectively, though bandwidth in excess of 10 GHz is feasible. LightSpin Technologies, Inc. proposed that scaling of single photon avalanche diode (SPAD) arrays to very tight pitches could be expected to achieve bandwidths in excess of 1 GHz, for the first time enabling simultaneous single photon detection and wide bandwidth operation in a solid-state detector. In Phase I, LightSpin demonstrated the capability to scale SPAD arrays to 11 micron pitch and demonstrated a bandwidth improvement in agreement with theory. In Phase II, we propose to continue the scaling effort to 5 micron pitch, enabling GHz and multi-GHz detection bandwidth with single photon sensitivity.