Analysis of photon heterodyne detection performance based on GM-APD pixel unit multiplexing

Laser heterodyne detection can obtain multidimensional information such as range, velocity, and micro-vibration. However, the traditional linear detection mode using PIN and APD photodiodes faces challenges of better sensitivity, especially in remote target detection. Developments of single photon detectors (SPD) such as the GM-APD array and SNSPD array provide the foundations for more robust and sensitive detection. Photon heterodyne detection (PHD) combines the advantages of heterodyne detection and single photon detection, which can obtain target multidimensional information with high sensitivity. The PHD performance is closely related to SPD working mode, and SPD single pixel detection mode requires a long accumulation time and the maximum photon count rate (PCR) is limited due to the dead time. In this paper, we propose a GM-APD pixel unit multiplexing (GPUM) method to improve the PHD performance. Theoretical analyses are conducted including the detection probability and SNR. The influence factors of coherent efficiency, photon number, and accumulative number are discussed in detail considering the PHD waveform recovery and SNR improvement. In addition, the heterodyne detection experiments are carried out using linear detection and photon detection, and the velocity extraction performance are analyzed in detail. This research is of significance to reveal the PHD process and optimize the coherent lidar systems design.