Theoretical analyses of laser modes for thermal deformation resonators

Laser modes in thermal deformation resonators are calculated and analyzed by means of perturbation methods. The coupling among laser modes and the relations between equivalent beam spread angle and the surface deformation of the mirrors are obtained. The theoretical results show that the bigger the thermal deformation at the center of a mirror and the stronger the coupling among laser modes, the more seriously the modes in a laser resonator are distorted. When the thermal deformation value at the center of a mirror is 0.5λ, the central laser intensity of TEM0 is reduced to 50% , and the equivalent beam spread angle is increased to 2 times of the ideal mirror．