Hybrid Integration of a Superconducting Nanowire Single‐Photon Detector Directly on the Fiber Facet

ABSTRACT Directly integrating superconducting nanowire single‐photon detectors (SNSPDs) on the fiber facet could significantly reduce coupling loss and alignment uncertainty, enabling an all‐fiber single‐photon detector with high detection efficiency, robust coupling, and compact size. However, the material and mechanical incompatibility between bulky optical fibers and nano‐fabricated ultrathin nanowires makes fabrication and integration challenging. Here, we demonstrate a hybrid integration method that involves fabricating individual membrane‐based detectors and optical mirrors separately, followed by their precise assembly on fiber facets. After integration, the detectors exhibit saturated quantum efficiency, a maximum system detection efficiency of 68.6%, a timing jitter as low as 26 ps, and a counting rate of up to 51.7 Mcps. These performance metrics are comparable to SNSPDs on standard silicon wafers. Moreover, this integration enables a fiber facet coupling regime where the detector is embedded in the guide mode of the incident light, resulting in an exceptionally broad detection bandwidth (1310–1640 nm) with less than 2.3% reduction in efficiency. The successful fiber facet integration of SNSPDs not only provides an alternative coupling strategy but also introduces a single‐photon detection capability into the group of fiber‐integrated optoelectronics, paving the way for low‐loss, long‐range quantum communication and distributed sensing systems.