Rise times of voltage pulses in NbN superconducting single-photon detectors

TL;DR

This paper investigates how the rise times of voltage pulses in NbN superconducting single-photon detectors increase nonlinearly with detector length, linking the effect to resistance and kinetic inductance based on experimental and theoretical analysis.

Contribution

It provides experimental data and theoretical modeling showing the nonlinear relationship between detector length and pulse rise time in NbN superconducting detectors.

Findings

Rise times increase nonlinearly with detector length.

Resistance after photon absorption depends on kinetic inductance.

The two-temperature model confirms the experimental observations.

Abstract

We have found experimentally that the rise times of voltage pulses in NbN superconducting single photon detectors increase nonlinearly with increasing detector length. We fabricated superconducting single photon detectors based on NbN thin films with a meander-like sensitive region of area from 2x2um2 to 11x11um2. The effect is connected with the dependence of the detector resistance, which appears after photon absorption, on its kinetic inductance and hence on detector length. This conclusion is confirmed by our calculations in the framework of the two-temperature model.