Achieving GHz system detection rate of photons in highly uniform responding superconducting nanowires coupled with multimode fiber

Single-photon detectors with high detection rates are the foundation for the high-speed remote laser communication. Although a total detection rate of gigahertz has been achieved with multiple superconducting nanowires, the coupled single-mode fibers are incompatible with most large-aperture optical telescopes, and the uneven response distribution between nanowires also limits the system performance in practice. Here, we report a multimode fiber coupled superconducting nanowire single-photon detector (SNSPD) with a gigahertz detection rate through 16 intertwined niobium nitride nanowires operated at 2.4 K. The SNSPD is coupled with a 62.5 μm multimode fiber through beam compression. Overcoming the interference of speckles in multimode fibers, all nanowires perform highly uniform with narrow distributions of detection efficiencies (5.48% ± 0.136%), achieving a total detection efficiency of 87.6% and a total system detection efficiency of 52.3%, a maximum detection rate of 1.3 Gcps when the efficiency drops by 3 dB, and a highest detection rate of 3.1 Gcps before latching occurs. The significance of the uniform performance of pixels in terms of system speed is verified by modeling the combined detection rate vs the detection efficiency distribution, which is crucial in high-speed laser communication.