Study On Single-frequency Pulsed Laser Used In Eye-safe Coherent Wind Lidar System

The precise detection of the atmospheric wind field plays an important role in predicting global climate change and accurate weather forecasting.Eye-safe Coherent Wind Lidars(CWL)are used for the precise detection of the atmospheric wind field.This thesis discusses design research on single-frequency pulsed laser used in eye-safe CWL system.In chapter 1,the basic structure and history of the Doppler CWL are summarized,and the current status of the CWL is analyzed in detail.Several typical CWL,1.6 ?m Er:YAG singlefrequency injection-seeded lasers are discussed.Based on the above studies,the seeding injection technology is employed to achieve Er:YAG single-frequency laser pulses.In chapter 2,the level structure and spectral characteristic of Er:YAG laser crystal are analyzed.The thermal effects in diode end-pumped and two-end-pumped Er:YAG lasers are discussed.A thermo-mechanical coupling model is constituted for Finite Element analysis based on the above results,and the focal length of the diode end-pumped Er:YAG laser is obtained by using this thermo-mechanical coupling model.The predicted thermal lensing values are compared with experimental results,which agree well with the simulated results.In chapter 3,the quasi-three-level nature of Er:YAG lasers is described.A numerical model is studied and employed to predict the performance of the end-pumped CW Er:YAG laser.And then,the slave and the seed laser of Er:YAG single-frequency injection-seeded laser are built experimentally,4.8 m J output energy is achieved at 500 Hz repetition rate,which provides a reference for engineering design research on single-frequency pulsed laser.In chapter 4,the structure design and machine assembly of the Er:YAG single-frequency pulsed laser engineering prototype are introduced.Each components of this engineering prototype are designed with Solidworks,and the stresses of each components are checked by using Finite Element Method.The Er:YAG single-frequency pulsed laser is successfully equipped on a 600 mm × 600 mm optical baseboard.Finally,the output energy of 4 m J with repetition rate of 400 Hz is achieved with this engineering prototype.