High repetition rate, tunable mid-infrared vortex beam generation based on ZGP optical parametric oscillator

Abstract

We present a tunable, high-repetition-rate mid-infrared vortex laser based on ZnGeP₂ (ZGP) optical parametric oscillator (OPO) with a singly resonant plane-parallel cavity which was pumped by a 2.1 μm vortex laser. The signal wavelength was tunable from 3.4 to 4.1 μm by rotating the ZGP crystal, while the corresponding idler output ranged from 4.2 to 5.3 μm. The signal vortex beam retained the same topological charge as the pump, while the idler beam exhibited a Gaussian intensity profile. At pulse repetition frequency of 10 kHz, the system achieved maximum output powers of 6.5 W for the signal (3.89 μm) and 5 W for the idler (4.55 μm), with pulse widths of 60.3 ns and 54.8 ns, respectively. This work demonstrates a highly efficient and flexible approach to generating vortex beams in the mid-infrared, advancing the potential for applications in high-resolution imaging, spectroscopy, and nonlinear optics.