Generation of higher-order vortex modes from a Pr3+:YLF laser source

Herein, we report on the direct generation of red (640 nm) and orange (607 nm) higher-order LG modes from the Pr³⁺:LiYF₄ (Pr³⁺:YLF) laser with an intra-cavity plano-convex spherical lens. The strong spherical aberration of the intra-cavity lens allows the oscillation of red higher-order LG modes represented by the coherent superposition of degenerated LG modes with positive and negative orbital angular momentum (OAM), |ℓ|≤31. A desired higher-order LG mode is selectively generated from the laser cavity simply by adjusting an on-axis position of the intra-cavity lens. Also, the system enables the generation of orange higher-order LG modes coherently superposed by degenerated positive and negative LG modes with |ℓ|≤17.