‘Elementary’ pulses in the response of a superconducting hot-electron bolometer to terahertz photons
T. I. Novikova, A. V. Osipenkov, P. Prudkovskii +1 more
Abstract Statistical characteristics of the photoresponse of a superconducting hot-electron bolometer detector were measured under illumination by low-power terahertz pulses of 25 ns duration and 1.5 THz frequency. The pulses were generated via nonlinear-optical effects of parametric down-conversion in Mg:LiNbO 3 crystal, which was cooled to 4.5 K and pumped by a pulsed laser. The asymmetric experimental histograms of the photoresponse values obtained at different levels of incident radiation power were approximated by the Poisson-weighted sum of functions representing the convolutions of varying numbers of Gaussian distributions of elementary photocurrent pulses and the dark current distribution. It was found that the average number, the mean value, and the variance of such elementary pulses change with incident power. Specifically, the mean value and standard deviation of these pulses both grow monotonically with the increase in the mean current response, while their number tends to reach saturation at high powers. Conclusions were made about the fluctuating nature of elementary pulses, which is related to the formation of different configurations of hot spots appearing due to absorption of photons in different areas of the superconducting film. An estimate of the maximum lifetime of a hot spot was made based on the experimental data.
Laser Physics Letters•Mar 31, 2026•1 citation