Superconducting Nanowire Single-Photon Detector (SNSPD) with 3D-Printed Free-Form Microlenses

TL;DR

This paper introduces a novel method to enhance SNSPD efficiency by printing free-form microlenses directly onto the detector, significantly increasing the effective collection area without compromising speed or fabrication yield.

Contribution

The study demonstrates the integration of 3D-printed microlenses on SNSPDs, achieving a 100-fold increase in collection area and improving detection efficiency for free-space optical detection.

Findings

100-fold increase in effective collection area

Enhanced detection efficiency at 1550 nm wavelength

Applicable to various sensor types without long nanowires

Abstract

We present an approach to increase the effective light-receiving area of superconducting nanowire single-photon detectors (SNSPD) by means of free-form microlenses that are printed in situ on top of the sensitive detector area using high-resolution multi-photon lithography. We demonstrate a detector based on a niobium-nitride (NbN) nanowire with a 4.5 $\mathrm \mu$m $\times$ 4.5 $\mathrm \mu$m sensitive area, supplemented with a lens of 60 $\mathrm \mu$m diameter. For free-space illumination at a wavelength of 1550 nm, the lensed sensor has a 100-fold-increased effective collection area, which leads to strongly enhanced system detection efficiency without the need for long nanowires. Our approach can be readily applied to a wide range of sensor types and effectively overcomes the inherent design conflict between high counting speed due to short sensor reset time, high timing accuracy, and high fabrication yield on the one hand and high collection efficiency through large effective detection areas on the other hand.