Optical Manipulation of Azimuthally Polarized Beam Altered by Phase Plate

The ring focus evolution of the azimuthally polarized beam induced by a pure two-portion phase plate is investigated. The pure phase plate consists of two concentric portions, center circle portion, and outer annular portion. When the phase of the center portion is pi, one ring focus may evolve into novel focal patterns with increasing radius of the center circle portion, such as cylindrical crust focus, two-ring focus, and three-ring focus. And if the geometrical parameters keep unchanged, focal patterns also changes considerably with tunable phase of the center portion. Ring focus shifts along optical axis with the increasing phase. The ring focus altered by the phase plate can be used in optical manipulation and material processing technologies.