Design of NbN superconducting nanowire single photon detectors with enhanced infrared photon detection efficiency

TL;DR

This paper presents an optimized design for NbN superconducting nanowire single photon detectors, enhancing infrared photon detection efficiency through geometry adjustments and nanowire deposition techniques.

Contribution

It introduces a novel design approach based on position-dependent detection efficiency and finite-difference-time-domain simulations to improve detector performance.

Findings

Optimal wire width is ~100 nm for 1550 nm wavelength.

Edge absorption can be increased with silicon nanowire overlay.

Design trade-offs between absorption and edge effects are identified.

Abstract

We propose an optimized design for nanowire superconducting single photon detectors, using the recently discovered position dependent detection efficiency in these devices. This knowledge allows an optimized the design of meandering wire NbN detectors by altering the field distribution across the wire. In order to calculate the response of the detectors with different geometries, we use a monotonic local detection efficiency from a nanowire and optical absorption distribution via finite-different-time-domain simulations. The calculations predict a trade-off between average absorption and the edge effect leading to a predicted optimal wire width close to 100 nm for 1550 nm wavelength, which drops to 50 nm wire width for 600 nm wavelength. The absorption at the edges can be enhanced by depositing a silicon nanowire on top of the superconducting nanowire, which improves both the total absorption efficiency as well as the internal detection efficiency of meandering wire structures.