All Solid-state High-power Nd: Yag Laser And Its Second And Fourth Harmonic Study

Laser diode pumped all-solid-state lasers have many advantages, such as light weight, compactness, efficiency, good beam quality, long life time, and so on. They have been applied in the fields of military, industry, medical treatment, research and communication, and have replaced the traditional lasers, like dye-laser, gas-laser, and so on. The application of laser has been expended by using the nonlinear optical frequency conversion technology. For example, high power solid state green lasers have attracted much attention in numerous applications such as laser medicine, laser display, and so on. The ultraviolet laser with shorter wave length has the unique superiority in precision machining, lithography, high-resolution printing.The main contents of this dissertation are as follows,1. The intensity distribution of multi-side pumped light has been analyzed theoretically, corresponding to different pumping parameters. With the three-side pumped condition, the heat conduct equation has been build up, and the temperature profile in the gain medium has also been simulated. Then the relation between the temperature gradient and the thermal focal length has also been discussed, and the compensation methods of the thermal focal length are provided. At last, we calculate the overlap integral between the pumping light and the oscillating light, and discuss the influence factors of the threshold pumping power and the slop efficiency.2. In this dissertation, the properties of several UV nonlinear optical crystals has been summarized, and some parameters of the negative uniaxial optical crystal has also been calculated, such as phase matching angle, effective nonlinear coefficient, and discussed some problems in the process of angle phase matching. Then the moisture preventive measure of the CLBO crystal has been discussed as well.3. The theories of second-harmonic generation with the plane wave approximation and the focused gaussian beam have been discussed. The selection of the focal length of the focusing lens has also been provided. In the end, we have analyzed the impaction of the temperature change of the nonlinear crystal on the frequency doubling efficiency. 4. After comparative analyzing the impaction of the cavity parameters on the system stability of both plano-plano cavity and the plano-concave cavity, a set of optimal parameters for our experiment has been selected. We then experimentally demonstrate a high power 532nm A-O Q-switched intracavity frequency doubling green laser system in a linear cavity, At incident pump current of 46 A, a maximum QCW output of 80W green laser is achieved. Then we demonstrate a complex cavity that can make the fundamental wave and the frequency doubled wave oscillated simultaneously. On this basis, after focusing the green laser into a type I phased BBO crystal, a UV output at 266nm of 607mW has been achieved with an incident current of 32.2A. Changing the focal length, and use the CLBO crystal to carry on the experiment. At the pumping current of 40A, we get a 7.1W 266nm output using a 70mm focal length of the lens. Finally, we analyze the influence of the cutting way of the CLBO crystal on the conversion efficiency.