Generation of Higher Order Vortex Beams From a YVO4/Nd:YVO4 Self-Raman Laser via Off-Axis Pumping With Mode Converter

The generation of high-order Hermite-Gaussian (HG) beams at the Stokes wavelength in a YVO
₄
/Nd:YVO
₄
self-Raman laser with off-axis pumping is demonstrated. The high-order vortex beams at the Stokes field are successfully created by transforming these HG modes via an extra-cavity mode converter. The stimulated Raman scattering (SRS) threshold pump power for the diode-end-pumped laser is theoretically analyzed to verify the feasibility of generating high-order HG modes by off-axis pumping. At a pump power of 18.6 W, the SRS output powers can be higher than 1.0 W for the HG modes from TEM
_0,0
to TEM
_3,0
. Under the same pump power, the maximum order can be up to TEM
_28,0
.