Integrated Waveguide Grating Vortex Laser Generator Directly Written in Nd:YAG Crystal

We report a waveguide-grating vortex laser generator processed by femtosecond laser direct writing in Nd:YAG crystal. Confocal micro-Raman measurement reveals the formation mechanism of the periodic refractive index modulation of the fork grating. The waveguide combing fork grating structure exhibits excellent single-mode guiding and vortex mode diffraction features, respectively. Furthermore, vortex laser is achieved at a wavelength of 1064.5 nm with a pump laser at 808 nm.