Range walk error compensation for SLR using fiber-coupled SNSPDs based on differential attenuation method

In satellite laser ranging (SLR) applications, the array superconducting nanowire single photon detectors (SNSPDs) introduce the range walk error due to the response characteristics, which affects the ranging accuracy. To reduce the impact of range walk errors, what we believe to be a novel experimental approach, termed the differential attenuation walk compensation (DAWC) method, is proposed based on a comprehensive theoretical analysis of the influencing factors. By establishing a detection probability model that incorporates factors such as echo pulse energy, time jitter, and pulse width, this study systematically examines the contributions of various factors to range walk errors. Theoretical analysis indicates that attenuating the echo signal to the single-photon level and leveraging the differential delay between the reference arm and the measurement arm can effectively compensate the range walk error. To validate this approach, experimental studies are conducted, incorporating a corner reflector positioned behind the secondary mirror and a fiber optic attenuator placed before the SNSPDs. The experimental results demonstrate that the strategy enhances the ranging accuracy by 0.14 ns in terms of RMS. This corresponds to an effective compensation of at least 40%. This method provides a promising solution for improving the precision of SLR.