Effects of extrinsic parameters on superconducting nanowire single-photon detector output – A study towards developing read-out circuit

A superconducting nanowire single-photon detector (SNSPD) is an optoelectrical device that works on the concept of hotspot formation and can detect a single photon. The associated readout circuit plays a vital role in determining the response of SNSPD. The available resources, complexity, and costs are major limiting factors in the actual readout circuit design. The preliminary information about the extrinsic effects that alter the SNSPD output from its desired value helps fabricate readout circuits. Here, the electrical equivalent circuit (EEC) for SNSPD has been simulated using LT spice software, and accordingly, a model has been developed to understand the readout circuit requirements. The EEC has been tested at room temperature by varying parameters like pulse width, bias voltage, capacitance and inductance. In addition, we have also designed and simulated a circuit for the multi-pixel photon counting scheme using a frequency multiplexing technique. Utilising this scheme, we observed that each EEC could be distinguished by its unique resonance frequency, reducing circuit complexity and power consumption. The results obtained indicate that their unique resonance frequency can identify triggered EEC.