| As the deterioration of climatic environment, requirements for atmospheric wind field data have become more urgent. Coherent doppler lidar(CDL) has caught many countries'attention. On account of the advantages including small size, low cost, low atmospheric extinction ratio, eye-safe, etc., 2μm solid-state laser is thought to be the preferred laser source for coherent doppler lidar. The output pulse of the laser using injection-locked technique can meet the requirements of coherent Doppler lidar to laser source, which needs not only single-longitudinal-mode, narrow linewidth, high-frequency stability, but also enough single pulse energy and enough pulsewidth. The injection-locked laser consists of master laser, slave laser and injection-locked servo system. In this paper,injection-locked 2μm solid-state laser has been investigated and explored theoretically and experimentally.Firstly, absorption spectrum in visible and infrared band, emission spectrum in infrared band and fluorescence lifetime are measured and compared. The absorption coefficient and emission cross-section are obtained. And according to the experimental data combined with fine structure of energy level splitting in Tm,Ho:YLF, the necessary parameters for the mode of Tm,Ho Laser are calculated. The data provides the basis for theoretical analysis and experimental research on Tm, Ho lasers.Theoretically, based on level translation and energy transfer of Tm,Ho co-doped laser, the quasi-four-level rate equations of CW Tm,Ho laser operated in cryogenic temperature are given. The relationship of population inversion and pump power is deduced, and the influence of Tm3+ concentration on pump quantum efficiency is discussed. These analytical formulas of initial upper level population inversion density and pulsewidth are obtained for the first time, and output pulsewidth is mainly discussed. The formula of dynamic-static ratio in Q-switch Tm,Ho co-doped laser is given. Influence of pulse repeat frequency and upper level lifetime on dynamic-static ratio is discussed. The conclusion is reached that pulse pump is the effective means to improve the dynamic-static ratio while a laser is operating at low pulse repeat frequency. In aspect of injection-locked theory, influence of seed injection on initial photon field is introduced. We discuss the maximum frequency detuning range and minimum seed injected power, and place emphasis on injection-locked longitudinal mode matching as well as transverse mode matching. The calculation expression of maximum frequency detuning in the experiment is given. The theoretical foundation is laid for experimental research on injection-locked 2mm solid-state laser by the studies above.Experimentally, injection-locked 2mm solid-state laser is designed and completed. Firstly, the lasing performance of microchip lasers in different matrixes are studied in detail. It is a conclusion that higher output power of single-longitudinal-mode laser can be obtained by lowering the matching between the pump light and oscillating light. Comparative researches of 0.9mm microchip laser, 0.5mm microchip laser and composite cavity structure laser are carried out. Reducing the effective cavity length is a feasible way to obtain higher single-longitudinal-mode output power. However, the beam quality and the distribution of the far-field variation of the laser will take a bad turn at the same time.Secondly, the ring laser as the power laser is studied. Making use of ABCD matrices, the ring cavity is analyzed and optimally designed. Experimental studies on continuous wave and Q-switched laser are carried out. The influences on the Tm, Ho: YLF laser performances induced by the cavity length and output coupling transmission of the resonator are also investigated. Main research is focused on two aspects. One is the relationship between single pulse energy and cavity length, output coupler transmission, pulsewidth. The other is single pulse energy, pulsewidth, peak power, and dynamic-static ratio in Q-switched operation as a function of pulse repetition frequency.Finally, the experimental research of injection-locked laser is carried out. The coupling system for the transverse mode matching between seed laser and ring cavity is designed in order to improve the utilization of the seed power, the injection-locked servo system is also designed so that longitudinal mode matching can be controlled precisely. Moreover, the timing relationship between various components is given. Characteristics of injection-locking laser are studied. The maximum frequency detuning range is measured by increasing the output power of seed laser to 16mW.
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