The Laser Resonators With Gaussian Gradual Reflectivity Output Mirror And It's The Beam Quality

The solid state lasers are getting more favor because it's advantages of small bulk, light weight, long service time, high transferring efficiency and so on. In recent years, the domains of laser have got more and more development because the all solid-state laser emerged and quickly enlarged. A lot of application of the solid state lasers requests high quality of the laser beam. And so, it is especial important that the investigating of the effect on the laser beam quality of the changing resonator length. In order to get high beam quality, it is necessary that to choose the structure of resonators and to adjust the resonator mirrors and the resonator length. This paper discusses following two points on the base of the influence of the structure and the length of resonators on the output beam quality:(1) We investigate the effect on the output laser beam quality of the difference resonator length of the Gaussian positive-branch confocal unstable resonators. The laser crystal is Nd:YAG rod and pumped by Xenon lamp. With help of the observation of the experimental result and the comparing between the Gaussian positive-branch confocal unstable resonators and the other, we found that the M2 value of the Gaussian positive-branch confocal unstable resonator is minimum, and so the beam quality of the Gaussian mirror unstable resonat is better than that of the other. But the M2 vlaue is sensitive to the changing of resonator length and so,the larger of M2 vlaue the more distance between the focus of two mirrors. In addition, the beam quality of same type of Gaussian confocal unstable resonators is obviously differnce from each other for different parameter of cavity mirrors. The smaller of diameter of the output Gaussian mirror, the better beam quality .(2) We have firstly discussed in theory and experiment about the structure of the resonator with plane Gaussian mirror and the beam quality under the condition of the LD side pump Nd:YAG solid state laser. Through the contrast between the gradual reflectivity mirror and uniform reflectivity mirror, we find that the high-order modes can be efficiently restrained by using Gaussian mirror as the output mirror, and also, the energy distribution is much more uniform. In the experiment, we find that when the Semiconductor Diode side pump solid state laser operates continually with the power of 3W, the laser transverse mode is TEM01 . But the mode is increased from lower-order to higher-order with the power increasing.