Research On The Application Of Photon-Counting Laser Pulse Detection

Laser pulse detection is a key generic technology in lidar and laser communication.It is an important research direction to improve system performance by improving the sensitivity of laser pulse detection.The detection sensitivity of the laser pulse detection can be promoted to single-photon or few-photon level by using single-photon detectors,which opens up new technical potential for the development of lidar and laser communication.However,single photon detectors have many technical bottlenecks in laser pulse detection applications.The main reason is that these applications were first developed based on linear photoelectric detection.The output of the photoelectric signal has a linear relationship with the incident light intensity,and has a large dynamic range of intensity.A reasonable threshold can be set to suppress background noise in order to discriminate signals.But the traditional single-photon detector has only two output photon states of "presence" or "absence",which is easy to be saturated or damaged by strong background light and cannot identify the signal by intensity.In order to solve this problem,this thesis developed high-speed & multi-channel single-photon detection technique and time-correlated photon-counting analysis method for fast discriminating signals.The photon-counting laser pulse detection technique has been developed for the applications of lidar and laser communication,and the experimental verification has been completed.The main innovations of the paper are as follows:1.Megahertz repetition rate photon-counting laser pulse detection technique.irst,in order to solve the technical bottleneck of low detection rate of nGaAs/InP APD single-photon detector in 1.5-?m eye-safety band,the GHz ine wave gated detection technique was used to increase the detection rate y nearly 2 orders of magnitude.Second,the multi-repetition-rate hoton-counting method has been developed with the laser pulses of 10 MHz.he unambiguous distance was increased by 2 orders of magnitude up to 165 m,which solved the contradiction between fast time-correlated ingle-photon counting and measurement range.Finally,the photon-counting ull-waveform analysis method has been developed with the laser pulses of 2 Hz,which not only improved the range accuracy,but also obtained the nformation of spatial vertical distribution,amplitude,pulse width,and ntensity of the echo pulse.The characteristics of the target surface were btained to realize the identification and classification of different targets.ased on such technique,this thesis completed photon-counting laser ranging xperiments with the distances of 21 km and 32 km in Qinghai Lake.2.The photon-number-resolving laser pulse detection technique.This thesis eveloped the photon-number-resolving detection technique with ulti-channel single-photon detector.It increased the dynamic range of ingle-photon detector.The photon number threshold was set to suppress ackground noise effectively based on the analysis of the photon number tates,which realized the discrimination of photon signals within single pulse.ased on such technique,this thesis carried out a 1.2-km all-day free-space aser communication experiment.The photon pulse signals were effectively dentified under strong background noise counts of 6 Mcps with the code eneration ratio of laser communication as high as 99.5%.