Dual waveband generator of perfect vector beams

Recently, the perfect vector (PV) beam has sparked considerable interest because its radius is independent of the topological charge (TC), which has demonstrated special capabilities in optical manipulation, microscopy imaging, and laser micromachining. Previous research about the generation and manipulation of such PV beams only focuses on the linear optical fields. Therefore, the generation of nonlinear PV beams is still lacking. Here, we propose a dual waveband generator to simultaneously generate the PV beams in linear and nonlinear wavebands. In our experiment, PV beams with different polarization states are realized. It is proved that the polarization states of the generated PV beams can be flexibly adjusted by changing the axis direction of a half wave plate. The experimental results show that the radii of the generated PV beams are equal and independent of the TCs. With proper alteration of the nonlinear crystals, this approach could be further extended to other nonlinear processes, such as sum-frequency generation and difference-frequency generation. (C) 2019 Chinese Laser Press