Preliminary Study On Polarization Control In High Power Chemical Laser Resonator

Polarization is a important parameter of the laser, which contains information on the state of the laser system. It is necessary to study control method of polarization of the laser in order to study the processes occurring in the active medium of the laser, to control the mode composition and power, to explain different effects associated with the polarization characteristics of the radiation,to gain high quality and high power polarized light, to exploit application of high power laser.We use Jones matrix to analyze the eigen-polarization of normal resonator, resonator using anisotropy material, normal foldaway resonator. The conclusion is that the eigen-polarization of normal resonator and normal foldaway resonator is natural light. So we use phase retardance mirror and polarization beam splitter in resonator respectively, in order to obtain linearly polarized light while power doesn't decrease.While we measure the polarization of high power laser, the most important is attenuating the power. Then the principal problem is ensuring the conservation of the polarization in the course of attenuation. So we mainly attenuate power by two cuneiform prisms, accurately attenuate by a neutral attenuator, let the power of laser to come into the bound of polarimeter while the polarization is not changed. In the end, we measure the polarization of normal foldaway resonator, foldaway cavity with phase retardance mirror and polarization beam splitter and the powerwhile cavity with and without polarization beam splitter, then, analyze the difference of theory and experiment. If we use polarization beam splitter in resonator, the linearly polarized light is obtained while the power isn't decrease. If we use phase retardance mirror in resonator, the degree of polarization of laser nearly equal to zero. This is different from theoretical linear polarization. The reason is that light is superposition of two mutual orthogonal linear polarization modes.