Few-mode fiber coupled superconducting nanowire single-photon detectors for photon efficient optical communications

Abstract

The NASA Glenn Research Center's development of a high-photon efficiency real-time optical communications ground receiver has added superconducting nanowire single-photon detectors (SNSPDs) coupled with few-mode fibers (FMF). High data rate space-to-ground optical communication links require enhanced ground receiver sensitivity to reduce spacecraft transmitter constraints, and therefore require highly efficient coupling from fiber to detector. In the presence of atmospheric turbulence the received optical wavefront can be severely distorted introducing higher-order spatial mode components to the received signal. To reduce mode filtering and mismatch loss and the resulting degradations to detector coupling efficiency, we explore the use of few-mode fiber coupling to commercial single-pixel SNSPDs. Graded index 20-µm few-mode fibers allow the commercial single pixel SNSPD's active area to couple with equal efficiency as single mode fibers. Here we determine detector characteristics such as count rate, detection efficiency, dark counts, and jitter, as well as detection efficiencies for higher-order fiber spatial modes. Additionally, we assess the laboratory performance of the detectors in an optical system which emulates future deep space optical communications links.

Large-area microwire MoSi single-photon detectors at 1550 nm wavelength

“…The SNSPD (superconducting nanowire single-photon detector) is an ideal detector for a broad range of applications such as space communication [2], LIDAR [3] and quantum key distribution [4]. Following the first experimental demonstration of SNSPDs [5], several models have been proposed to explain the detection mechanism in nanowires [6].…”

A real-time optical ground receiver for photon starved environments

“…The photonic lantern can be scaled by changing the number of output fibers. For the photonic lantern architecture, the SNSPDs in use are commercial devices and have been characterized previously 6,7 .…”

16-Element Superconducting Nanowire Single-Photon Detector for Gigahertz Counting at 1550-nm

“…Net SDE across all elements was 83.4% with 71,000 dark counts per second. FMF laser sources are not readily available, but there has been an exploration 24 of how the higher order modes in the fiber couple to an SNSPD with similar total footprint to this one, and how the increased fiber core size affects dark rates compared to SMF coupling.…”