Mitigation of amplified spontaneous emission noise for an all-fiber coaxial aerosol lidar with different single-photon detectors.

For a coaxial single-photon lidar system, amplified spontaneous emission (ASE) noise from the fiber amplifier is inevitable. The ASE backscattering from specular reflection annihilates the far-field weak signal, resulting in low signal-to-noise ratio, short measurement distance, and even misidentification. We propose a method for calibrating and mitigating ASE noise in all-fiber coaxial aerosol lidar and demonstrate the method for a lidar system with different single-photon detectors (SPDs). The accuracy of the coaxial aerosol lidar is comparable to that of the biaxial one. We conducted an experiment using three different detectors, namely, InGaAs/InP SPD, up-conversion SPD, and superconducting nanowire SPD in the same coaxial lidar system. Compared with the biaxial system, the three different detectors we used have achieved more than 90% ASE noise suppression, the measured visibility percent errors of InGaAs/InP SPD data, up-conversion SPD data, and superconducting nanowire SPD data all within 20%, and the percent error within 10% are 99.47%, 100%, and 95.12%, respectively. Moreover, time-sharing optical switching allowed to obtain background noise with high accuracy.