We report the performance of a germanium quad-cell, composed of four avalanche photodiodes operated in the photon-counting regime, biased above the breakdown voltage. Each pixel detects a single photon in the wavelength range 1–1.5 μm with ~10% quantum efficiency and measures the photon arrival time with a time resolution of 100 ps. By adopting a multiplexed gating of the avalanche photodiodes we avoided the optical cross talk among pixels, thus achieving a noise-equivalent power of 3 × 10−15 W/Hz1/2 for each pixel and demonstrating the tracking capabilities of such a detector.
© 1996 Optical Society of America
F. Zappa, A. Lacaita, S. Cova, and P. Lovati, "Counting, timing, and tracking with a single-photon germanium detector," Opt. Lett. 21, 59-61 (1996)