Actively Q-switched and vortex Nd:YAG laser

We reported an efficient and actively Q-switched Nd:YAG laser that emitted the first order Laguerre-Gaussian mode with right-handedness helical wavefront. In the experiment, the pump light was converted into annular profile through off-focus coupling in a conventional multi-mode fiber. The laser cavity, consisting of a laser crystal and an output coupler and incorporating an acousto-optic Q switch and an etalon, was simple and compact. The Q-switched performance of the laser was given in detail.