ИСТИНА

The standard-free absolute method was proposed in 1980 by D.N. Klyshko for calibration of quantum effi ciencies of single-photon photodetectors. The method is based on measuring fluxes of quantum-correlated pairs of photons (“biphotons”) generated by spontaneous parametric down-conversion (SPDC) and does not require the use of any pre-calibrated detectors or sources. Now it is widely used in the modern quantum optical technologies, but so far is not adapted for analog detectors that generate single-photon photocurrent pulses with strongly different amplitudes and thus cannot operate in the photon counting mode. Among such devices, for example, are the majority of incoherent far infrared and terahertz wave detectors. The goal of this work was to create a modified Klyshko method for calibrating the quantum efficiency of such non-counting analog-type detectors. In order to find out how to calibrate detectors in the terahertz range, first we started our work with optical analog detectors. This is explained by the fact that the known to be accurately calibrated photon-counting detectors, which are necessary for application and verification of results of our new approach, are easily accessible in the optical range only.