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

摘要

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