Flattop focusing with full Poincaré beams under low numerical aperture illumination

In this Letter, we propose and experimentally demonstrate the generation of second-order full Poincaré beams and its applications in two-dimensional flattop beam shaping with spatially variant polarization under low NA focusing condition. High-quality flattop profiles with steep edge roll-off can be obtained with this technique. The experiment results also demonstrate that flattop profile can be maintained for different input beam sizes by conveniently rotating a half-wave plate.