Abstract:
New applications of superconducting single-photon detectors increase the requirement for large active area detectors. In this study we designed and fabricated a 12-pixel NbN detector with a large active area and a stripe width of 500 nm and an active area size of 45 $\mu$m $\times$ 50 $\mu$m, which is suitable for matching with multimode optical fiber. We investigated the current-voltage characteristics and determined the critical current $I_c$ of the sample. This value was compared with the maximum possible theoretical value of the depairing current $I_{dep}$. Due to the design of the multi-element NbN detector, which eliminates the influence of the current bunching effect, most of the studied samples demonstrate $I_c/I_{dep}$ value exceeding 0.7. Our results indicate that most of the pixels on the studied multi-element detector are capable of single photon detection.
Keywords:superconducting single-photon detectors, superconductivity, critical current of a superconductor, shunt resistor, volt-ampere characteristics.
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