Investigating the generation and propagation evolution of orange optical vortices using continuous-wave KGW Raman...

Various high-order orange beams (HOBs) at 588 nm are produced via off-center pumped Nd:YVO₄/KGW Raman lasers. We experimentally confirm that the HOBs can be fairly sustained at the incident pump power of 2.88 W, where the average output powers are overall from 300 mW to 160 mW with increasing the off-center displacements from 0.14 mm to 0.21 mm. The HOBs are further transformed by using an astigmatic mode converter to generate a variety of structured lights with optical vortices. Moreover, theoretical wave functions are analytically derived to characterize the propagation evolution of the converted HOBs. The experimental patterns for all propagating positions are excellently reconstructed by the derived wave functions, and the evolution of phase structures is numerically calculated to manifest the robust optical vortices.