Klyshko Method for Analog Photodetectors and Absolute Measurement of Photon Numbers

A modification of the Klyshko method is proposed for the reference-free calibration of analog photodetectors. It is shown that the photocurrent distribution of an analog detector can be approximated by a convolution of the Poisson distribution of the number of photoelectrons with a function describing single photopulses, and the number of photons incident on the detector can be determined from the statistical properties of biphoton radiation. The ratio of the number of photoelectrons to the number of photons gives the efficiency of the analog photodetector, which can be used to measure the intensity of the radiation incident on the detector in units of photon numbers.