Low-footprint fiber-coupled InGaAs/InP single-photon avalanche diode butterfly module

Compact single-photon detectors are essential components for field-deployable quantum technology systems, such as fiber-based quantum key distribution (QKD) receivers or time-of-flight sensors for ranging applications. In contrast to cryogenic superconducting nanowires, InGaAs/InP semiconductor-based single-photon avalanche diodes (SPADs) have significant advantages in terms of size, weight, power, and cost (SWaP-C) as they are only moderately cooled by thermoelectric coolers (TECs). In addition, the non-cryogenic temperatures provide a better reliability of the device and allow its use in non-academic applications. We present a significantly improved chip generation compared to previous results [1,2] with a system application oriented housing (fiber in-plane with PCB), by packaging the chip in a hermetic butterfly housing with fiber-pigtail and integrated TEC for cryo-free operation at temperatures down to -50°C, see Fig. 1.