Off-Axis Gaussian Beam Transfer through Unstable Resonator

Abstract

The transformation of the Rayleigh length and the position of axis of an off-axis Gaussian beam by unstable confocal resonator is studied, taking into account the geometric magnification parameter M, the shear parameter, and the initial characteristics of the incident Gaussian beam. The results of calculations and experimental test of the Gaussian beams parameters are obtained for the opposite propagating beams in the resonator. It is shown that Rayleigh length of introduced and outgoing opposite Gaussian beams decrease and increase accordingly as an M2 after every round trip. Meanwhile, the distance between the axis of the off-axis Gaussian beam and the axis of resonator and shear parameter of decentered Gaussian beam are changed proportionally to M.