High-energy 2  µm pulsed vortex beam excitation from a Q-switched Tm:LuYAG laser

We report on the first, to the best of our knowledge, direct generation of pulsed vortex beams at 2 µm from a ${ Q}$Q-switched Tm:LuYAG laser. High-energy Laguerre-Gaussian (${{\rm LG}_{0,l}}$LG_0,l) pulsed laser beams with well-defined handedness are selectively excited through spatially matched pump gain distribution and asymmetric cavity loss without using any intracavity handedness-selective optical elements. Pulse energies of 1.48 mJ for the ${{\rm LG}_{0, + 1}}$LG_0,+1 mode and 1.51 mJ for the ${{\rm LG}_{0, - 1}}$LG_0,-1 mode, respectively, are achieved at a repetition rate of 500 Hz. The pulsed laser beams with helical wavefronts are potentially useful for studying orbital angular momentum transformation dynamics, generation of mid-IR vortex beams, and nanostructuring of organic materials.