Optical Engineering
Absolute meter of photodetector quantum efficiency based on the parametric down-conversion effect
Vera M. Ginzburg, N. G. Keratishvili, Y. L. Korzhenevich, G. V. Lunev, Alexander N. Penin, Victor I. Sapritsky
Abstract
The quantum phenomena of parametric down conversion have been used for absolute measurement of the photodetector quantum efficiency of ultra-low-light radiation ranging from 10-12 to 10-15 W, which is equivalent to photon fluxes of 107 to 104 s-1. The process of parametric down conversion gives rise to highly correlated (in time and space) photon flux pairs. We describe the method, experimental investigation, and a new device involving the measurement of the coincidence rate of photodetection of these two correlated beams of light. The coincidence is lowered by a nonunit quantum efficiency of either detection. This fact was used for the definition of the absolute value of both photodetector's quantum efficiencies.