Control of Vortex Helicity With a Quarter-Wave Plate in an Er:YAG Ceramic Solid State Laser

In this paper, we research the characteristics of the Laguerre-Gaussian (LG
₀₁
) beams generated in an Er:YAG ceramic solid state laser pumped by an annular beam. The generated two LG
₀₁
beams (LG
_0,+1
and LG
_0,−1
modes) were found to have different thermally induced polarization behaviors and alternately existed in the resonator; then, a novel method was proposed and experimentally demonstrated to control the vortex helicity using a simple quarter-wave plate.