MEASUREMENT OF THE EFFICIENCY OF DETECTION BY SINGLE-PHOTON COUNTERS BASED ON AVALANCHE PHOTODIODES BY THE METHOD OF SPONTANEOUS PARAMETRIC DOWN CONVERSION WITH SPECTRALLY ASYMMETRIC CHANNELS

We consider a frequency-diaphragm technique of simultaneous standardless measurements of the efficiency of photon detection by two single-photon counters. This technique is based on the well-known scheme of measurements of the efficiency of detection of single photons with the help of photon pairs generated in a nonlinear crystal in the case of spontaneous parametric scattering. As a specific feature of the proposed procedure, we can mention the application of spectrally asymmetric optical channels. An experimental installation aimed at the realization of the proposed procedure in the degenerate mode of spontaneous parametric scattering is described. The results of simultaneous measurements of the detection efficiency of two single-photon counters at a wavelength of 810 nm are presented. The counters are constructed on the basis of SAP-500 silicon avalanche photodiodes with fiber inputs. It is shown that this technique can be also used for measuring the detection efficiency of single-photon counters sensitive in a more long-wave region of the spectrum. As compared with the pure diaphragm scheme, the proposed procedures has advantages in the simplicity and reliability of adjustment.