A highly sensitive photodetection system with a detection limit of 1 photon/s was developed. This system uses a commercially available 200-mm-diameter silicon avalanche photodiode (APD) and an in-house-developed ultralow-noise readout circuit, which are both cooled to 77 K. When the APD operates at a low gain of about 10, it has a high-linearity response to the number of incident photons and a low excess noise factor. The APD also has high quantum efficiency and a dark current of less than 1 e/s at 77 K. This photodetection system will shorten the measurement time and enable higher spatial and wavelength resolution for near-field scanning optical microscopes.
@article{arxiv.quant-ph/0503048,
title = {Ultrahigh-sensitivity high-linearity photodetection system using a low-gain avalanche photodiode with an ultralow-noise readout circuit},
author = {Makoto Akiba and Mikio Fujiwara and Masahide Sasaki},
journal= {arXiv preprint arXiv:quant-ph/0503048},
year = {2009}
}