PHOTON-COUNTING USING A LARGE-AREA AVALANCHE PHOTODIODE COOLED TO 100-K

We have detected single 650 nm photons with quantum efficiencies great er than 60% using a large area silicon avalanche photodiode. We cool a 5 mm diam commercially available device to 100 K and operate in the g ain-mode. For most applications-from the near-infrared to the ultravio let-this device is the most sensitive photon counting detector that ha s ever been demonstrated. In typical photon counting applications, thi s detector should prove to be between two and one hundred times more s ensitive than the best currently available devices.