Research Of Single-photon Detection Technology In Lidar Applications

Light detection and ranging(Lidar)is widely used in military,atmospheric science,environmental monitoring and other fields due to its strong directivity and high resolution.Among numerous kind of lidars,1.5 ?m lidar has advantages of eye safe,high atmospheric transmittance and weak solar background radiation,which is especially suitable for applications in human activity area,such as long-distance single photon three-dimensional imaging,urban pollution monitoring,airport wind speed measurement,etc.240?280 nm mid ultraviolet lidar has the characteristics of solar blindness and strong Rayleigh scattering,which is suitable for the detection of aircraft plume and the detection of atmospheric wind field in the stratosphere.Generally,lidar signal weakens quickly with the increase of detection range due to the absorption and scattering of atmosphere and the reduction of solid angle.Using single-photon detector for receiving the weak echo signal can significantly increase the signal-to-noise ratio and increase maximum detection range.It also reduces the requirements of laser energy and telescope aperture,which is conducive to build miniaturized and integrated lidar system.However,commercial silicon single photon detectors have no response at 1.5 ?m and mid ultraviolet wavelength.Near-infrared and mid ultraviolet single photon detectors are urgently needed at the moment.Under the background,this dissertation focuses on the single photon detection technologies for 1.5 ?m and mid ultraviolet lidars.The main works include:In the direction of near infrared single-photon detection,the author developed a free-running single-photon detector prototype based on InGaAs/InP negative feedback avalanche photodiode.The performance calibration systems for single-mode and multi-mode optical-coupled detectors have been built respectively.The InGaAs/InP free-running single photon detector is applied to a high precision aerosol lidar system,and a counting rate correction algorithm and an afterpulse correction algorithm were proposed.The average error between the corrected lidar signal and the signal detected by a high performance superconducting nano wire single photon detector was only 13%.Then,a compact and practical cloud lidar and an unmanned aerosol lidar are developed.In the application of long-range single-photon three-dimensional imaging,a miniaturized ultra-low noise InGaAs/InP free-running single-photon detector coupled with multimode fibers has been developed,and high-precision time measurement of detection signal has been achieved in the detector,which provides strong support for the development of practical ultra-long-range single-photon three-dimensional imaging lidar.In the direction of mid-ultraviolet single-photon detection,the author developed a single-photon detector based on 4H-SiC single-photon avalanche photodiode,and designed an automatic performance calibration system for free-space coupling.The performance of 4H-SiC single-photon avalanche photodiode includes the detection efficiency distribution on photosensitive area,avalanche signal amplitude distribution,dark count rate,detection efficiency and afterpulse probability was carefully characterized.The main innovations of this article are as follows:1.An integrated and practical InGaAs/InP free-running single-photon detector is designed,with a maximum detection efficiency of 40%;2.A counting rate correction algorithm and an afterpulse correction algorithm for free-running single-photon detectors have been developed,which lay a foundation for the application of InGaAs/InP single-photon detectors in high-precision aerosol lidar.3.A miniaturized ultra-low noise InGaAs/InP free-running mode single photon detector coupled with multimode optical fiber has been developed,with dark counting rate of only 100 cps at 20%detection efficiency.The detector is applied to ultra-long range single-photon three-dimensional imaging lidar system,and finally achieved longest detection range in the world.