Numerical investigation on the generation of high-order Laguerre-Gaussian beams in end-pumped solid-state lasers by introducing loss control.

This paper reports a robust and systematic approach to generate high-order scalar Laguerre-Gaussian (LG_p,l) beams in end-pumped solid-state lasers by introducing loss control. Based on the spatial distributions of Laguerre-Gaussian modes and the theory of transverse mode selection, the "loss control" is implemented by an amplitude mask in the resonator. This proposed mechanism can be divided into three categories: radial loss, azimuthal loss, and the combination of radial and azimuthal loss, which correspond to excite radial high-order modes (LG_p,0), azimuthal high-order modes (LG_0,l), and regular high-order modes (LG_p,l), respectively. By controlling the locations and thicknesses of opaque rings and lines on the mask, all kinds of LG_p,l modes can be obtained. With the application of mode purity, all the generated modes possess high mode purities greater than 93% in simulation.