Development process towards a cost-effective single-photon detector

This study explores advancements in the design of single-photon detectors (SPDs) by first reviewing conventional development approaches. The performance of avalanche photodiodes (APDs) was systematically investigated across varying reverse bias voltages, operating temperatures, and passive quenching resistances, providing new insights into their suitability as sensors for SPD applications. The focus of this work was to identify the most cost-effective APD for reliable single-photon detection. Notably, substituting bipolar junction transistors with an operational amplifier (op-amp) as the first-stage amplifier simplified the design. In addition, a comparative evaluation of the traditional transimpedance amplifier configuration and a voltage amplifier revealed that the latter significantly increased the first-stage gain. We investigated the detection limits of the single-photon detectors by attenuating the excitation laser with neutral density filters. Collectively, these methodological refinements enabled the system to achieve photon-counting approaching single-photon events, underscoring its potential for practical and economical SPD implementation.