Cryogenic DC-coupled readout electronics for high-speed superconducting nanowire single-photon detectors based on a commercial operational amplifier

Abstract

Superconducting nanowire single-photon detectors (SNSPD) have the advantages of high maximal counting rate (MCR), high detection efficiency, and low dark count rate. They play an important role in the fields of optical quantum communication, optical quantum computing, laser ranging, and imaging. The MCR (i.e. detection speed) of SNSPD can be affected by the front-end readout circuit. To increase MCR, it is usually necessary to use a cryogenic DC-coupled readout circuit with a broad bandwidth. This study reports an SNSPD cryogenic DC-coupled amplification readout circuit based on a commercial high-speed operational amplifier chip OPA855. We systematically characterize its performance parameters in a temperature range from a room temperature of 300 K to a low temperature of 4.2 K. We address the problem of bandwidth loss of the circuit in a low-temperature environment by increasing the operating voltage of the OPA855 chip. For example, at 40 K, the operating voltage increases from ±2.5 V to ±4.9 V, and the quiescent current is about 8 mA, which is equivalent to a power consumption of 78 mW; meanwhile, the gain of this readout circuit is 16.7 dB, and the –3 dB cutoff bandwidth is ~2.7 GHz. We further install a cryogenic DC-coupled readout circuit based on the OPA855 amplifier at 40 K and characterize the performance parameters of the SNSPD at 2.2 K, such as the switching current, system detection efficiency, and MCR. The comparison with the conventional AC-coupled readout circuit at room temperature shows that the MCR increases about 1.3 times after using the DC-coupling circuit. Our study provides the interesting information about the OPA855 amplifier’s performance at low temperatures which facilitates its application in cryogenic environments and related fields.