Controlling the handedness of directly excited Laguerre–Gaussian modes in a solid-state laser

In this Letter, we report a novel approach for directly exciting the lowest-order Laguerre-Gaussian (LG₀₁) donut mode with controllable handedness of the helical phase front trajectory in an end-pumped solid-state laser. Our approach is based on the use of a novel mode selection element consisting of two nanoscale thickness aluminum stripes to provide discrimination between LG₀₁ modes with opposite handedness. This scheme has been applied to a diode-pumped Nd:YAG laser to generate and switch between LG₀₁ modes with opposite handedness at output powers ~1 W at 1064 nm.