Application Of GLAD For Simulation Of Laser Resonator

The structure of laser resonator largely determines the quality of output beam of a laser. It is most important for lasers to get good resonant cavities to obtain high performance operation. In practice there are always some error factors, which make the actual optical field deviate from the ideal optical field. Therefore, research on the effect of error factors on resonator modes is particularly important.In this paper, the effects of non-ideal factors on the resonator mode are simulated, mainly analyzed by the software of GLAD, which is an physical optical analysis software and can process diffraction effects in optical design mainly with FFT method.Firstly, theories about resonator mode and work interface of GLAD and function of each part are introduced. And then the numerical methods about diffraction propagation of light in the software are derived in detail. Finally, GLAD is applied to the simulation of the resonant cavity mode. In the case of ideal and non-ideal situation, modes and losses of a stable resonator with two mirrors, a F-P cavity, an virtual confocal unstable resonator, a planar annular cavity with four mirrors and three mirrors are calculated, and the changes of modes and losses along with non-ideal factors are presented. The results show that the optical field distribution patterns in the cavity axis in the ideal case, which has the best quality and the minimum loss. Non-ideal factors cause distortion of the resonator mode. The deviation of the field centroid from the cavity axis and the cavity loss increase along with increase of non-ideal factors. Due to influence of cavity structure, unstable resonators have the maximum loss and stable resonators have the minimum loss. Critical resonators are more sensitive to error factors. Generally speaking, small apertures have defferent effects on resonator modes in defferent directions offset and mirror angular misalignments in different directions have different effects on resonator modes for planar ring cavities. For the existing mirror processing technology, the influence of mirror surface shape error on resonator modes is generally small. The aperture critical radius and the best radius are only related to the waist radius, and the ratio of them to the waist radius generally are certain values.