1.5μm All-Fiber Multifunction Coherent Doppler Wind Lidar

Beginning from the ground,the Earth’s atmosphere includes the troposphere,stratosphere,mesosphere,thermosphere,exosphere.The troposphere is the highest density layer,which contains about 80%of the mass of Earth’s atmosphere,and almost all water vapors and aerosols.The weather change in troposphere is also the most complex,and almost all weather changes that humans encounter in aviation and in their daily lives appear on this layer.The tropospheric wind field and atmospheric depolarization ratio are the key parameters for wind energy development and utilization,aviation safety,safety security of large buildings and major projects,and urban planning and disaster prevention management.They are also important parameters for dilution,diffusion and transportation of atmospheric pollutants.Lidar uses the amplitude,frequency,phase,and polarization of the laser to accurately measure distance,frequency shift,target angle and the polarization.Coherent Doppler wind lidar（CDWL）has compact structure,high angular resolution,high spatial and temporal resolution,high measurement accuracy,large dynamic range,long detection range,multi-target detection and strong anti-interference ability.This paper introduces the development of 1.5μm all-fiber multifunctional coherent Doppler wind lidar.The paper is divided into three chapters.The first chapter is the introduction.This section describes the application of CDWL in improving wind energy utilization,extreme weather warning,air pollution monitoring,large building security and solving scientific problems.The history of CDWL is reviewed.The second chapter is the theoretical derivation of CDWL.Based on BPLO,the expression of carrier-to-noise ratio of CDWL is derived,and the concept of antenna efficiency is introduced.The parameters of key components are optimized to improve the carrier-to-noise ratio of the lidar.Then based on the optimized system parameters,Monte Carlo simulation is used to generate backscattering data and process to obtain the theoretical CDWL’s performance.Finally,the comparison between the measured results of the lidar and the theoretical performance is used to prove the correctness of the theoretical derivation.The third chapter introduces the design,manufacturing process and experiment of CDWL.This chapter is divided into five parts:（1）1.5μm polarization coherent lidar incorporating time-division multiplexing.（2）Spatial resolution enhancement of coherent Doppler wind lidar using joint time-frequency analysis;（3）Meter-scale spatial resolution coherent Doppler wind lidar based on Golay coding;（4）Relationship analysis of PM_2.5and BLH using aerosol and turbulence detection lidar;（5）Comparison experiment between coherent Doppler wind lidar and air balloon in Anqing area.The stability and wide application scenarios of all-fiber multifunctional coherent Doppler wind lidar are fully verified by the above five experiments.