Abstract Body

Superconducting nanowire single-photon detectors (SNSPD) provide high efficiency and high speed, especially in optical communication system operating in low-flux conditions, such as deep-space. Further increasing the counting rate for achieving higher communication rate requires multi-pixel SNSPD arrays to overcome the kinetic inductance reset time limit of a conventional SNSPD. However, the number of readout lines would increase the complexity in signal processing and synchronization.

Here, we demonstrate a four-quadrant (2×2) array, covering an detection area of 10μm × 10 μm. Each quadrant detector was designed into a 3-pixel serial architecture. Each pixel was on-chip shunted with a 30 Ω resistor. This array was installed in a low-vibration 1.5 K cryostat and coupled through a single-mode fiber lens placed on a cryogenic 3-axes nanopositioner. All four quadrant detectors showed saturated quantum efficiency. By aligned the focused light on one quadrant detector, the maximum system detection efficiency reached 94%. The width of detection pulses was ~5 ns. At higher counting rate, pulses started piling up, which can be reconstructed after post processing. With this high efficiency and high speed detector array, laser communication experiments were demonstrated at a data rate of 2.4 Gbps in the format of pulse position modulation.

References

[1] Hao, H., Zhao, QY., Huang, YH. et al. A compact multi-pixel superconducting nanowire single-photon detector array supporting gigabit space-to-ground communications. Light Sci Appl 13, 25 (2024).

Figure 1. Detector architecture and performance. a. Stucture of the high-speed SNSPD. b. System detection efficiency versus bias current for the first quadrant detector.

Keywords: Superconducting nanowire single-photon detector, System detection efficiency, Single photon communication