Tunable near- and mid-infrared (1.36-1.63 µm and 3.07-4.81 µm) optical vortex laser source

The generation of near- and mid-infrared vortex mode is demonstrated from a 1 µm nanosecond optical vortex pumped optical parametric oscillator using a multi-grating MgO-doped periodically poled lithium niobate crystal with five grating domains. This system enables the orbital angular momentum between the signal and idler outputs to be exchanged simply by controlling the cavity Q-factor, and a vortex output in the wavelength ranges of 1.36-1.63 µm or 3.07-4.81 µm could be obtained. A maximum signal (idler) vortex output energy of 4.3 mJ (2.2 mJ) was achieved at a pump energy of 21 mJ, which corresponds to an optical-optical conversion efficiency of over 20% (10%).