Numerical modeling of SNSPD absorption utilizing optical conductivity with quantum corrections

TL;DR

This paper models the optical absorption of SNSPDs by incorporating quantum-corrected optical conductivity, revealing that material properties significantly influence wavelength range optimization beyond geometric factors.

Contribution

It introduces a numerical modeling approach that includes quantum corrections to optical conductivity, enhancing SNSPD design accuracy.

Findings

Optical conductivity ratio impacts detector wavelength range.

Material properties significantly influence absorption characteristics.

Quantum corrections improve modeling accuracy.

Abstract

Superconducting nanowire single-photon detectors are widely used in various fields of physics and technology, due to their high efficiency and timing precision. Although, in principle, their detection mechanism offers broadband operation, their wavelength range has to be optimized by the optical cavity parameters for a specific task. We present a study of the optical absorption of a superconducting nanowire single photon detector (SNSPD) with an optical cavity. The optical properties of the niobium nitride films, measured by spectroscopic ellipsometry, were modelled using the Drude-Lorentz model with quantum corrections. The numerical simulations of the optical response of the detectors show that the wavelength range of the detector is not solely determined by its geometry, but the optical conductivity of the disordered thin metallic films contributes considerably. This contribution can be conveniently expressed by the ratio of imaginary and real parts of the optical conductivity. This knowledge can be utilized in detector design.