Effect of the azimuthal gradient of the thermal load on the depolarization of cylindrical vector beams propagating in a side non-uniformly pumped isotropic medium

The theoretical and experimental investigations of the depolarization of cylindrical vector beams when they propagate into a side non-uniformly pumped isotropic laser medium. The azimuthal gradient of thermal load inside the cross-section of laser rod and its induced dynamic process on thermally induced birefringence are the internal mechanism of the depolarization of the cylindrical vector beams. The experiment results show that the depolarization degree is proportional to the azimuthal gradient. For the experiment level of depolarization, the maximum degrees of both radially and azimuthally polarized beams measured at the azimuthal gradient of 0.35 W/(mm(3).rad) were 3.1%.