Research On Injection Frequency-locked Technology Nd:YAG Laser With Single Corner Cube

Lidar based on the Doppler effect is widely used in atmospheric wind field measurement.Direct detection lidar technology has a wide range of applications.It can not only analyze the backscattered signals of aerosols,but also analyze the backscattered signals of individual gas molecules on a microscopic scale.The single-frequency laser in the 1μm band is a research hotspot.Injection frequency locking technology is a common method for radar light sources to obtain single-frequency output,high repetition frequency,narrow line width,short pulse width,and large energy.The pyramid resonator technology increases the anti-detuning performance of the laser and the stability of the laser output.In this thesis,the Nd:YAG injection frequency locking technology under a single pyramid is studied for the needs of lidar light sources.First,the paper compares the research status of single-frequency lasers at home and abroad,analyzes the method of Nd:YAG solid-state laser injection frequency-locking technology and summarizes the advantages and disadvantages of different methods,and finally determines the use of "Ramp-Hold-Fire" technology to obtain single-frequency output.In addition,the current research status of the debugging-free solid-state laser with the pyramid resonator is studied,and a method of using the pyramid resonator to compensate the PZT ringing effect in the "RampHold-Fire" technology is proposed,and the pulse energy stability is enhanced.The theoretical model of injection frequency locking is established,and the detuning amount of the master-slave laser frequency is analyzed during frequency locking.The theoretical model of the Nd:YAG active Q-switching rate equation is established,and the relationship between the energy extraction efficiency of the active Q-switched laser and the gain loss,as well as the relationship between the pulse width,energy and the number of inverted populations are analyzed.It provides theoretical guidance for subsequent injection frequency locking experiments.The Nd:YAG NPRO master laser was built as the seed light.The seed light continuously outputs a single longitudinal mode,and still meets the injection power demand after passing through the isolation system and the lens conversion system.A four-mirror ring cavity is designed as a slave laser,and the pumping range of the slave laser is analyzed with the ABCD matrix.Considering the enhancement of the stability of the resonant cavity,a pyramid is used to replace the four-mirror ring cavity mirror,and experiments have verified the compensation of the depolarization effect of the corner cube by the glass plate and the influence of the detuning angle on the loss of the resonant cavity.Finally,the mode matching of the master-slave laser was theoretically analyzed.The lens conversion system was used to realize the master-slave laser transverse mode matching,and the"Ramp-Hold-Fire" technology was used to realize the master-slave-laser longitudinal mode matching.A single-pyramidal Nd:YAG injection frequency-locked laser was built.At a repetition frequency of 200Hz,a single-frequency laser with a single pulse energy of 1.4mJ and a single pulse width of 37.00ns was obtained.The beam quality was M2=1.2 and the center wavelength was 1064.9nm.The energy stability was 0.98%.