Single-photon-counting APDs operate in the near-infrared

摘要

Linear- and Geiger-mode avalanche photodiodes made of III-V compound semiconductors will operate in the eye-safe region; the linear-mode versions will also offer photon-number discrimination. Single-photon counting poses considerable demands on detector design and fabrication. Although the actual absorption of each individual photon is a random event that obeys Poisson's distribution, a 1 W beam of 1540 nm light delivers one photon every 1.29 X 10~(-19) second, on average.