Three-Dimensional Intensity Distribution by a Pure Phase Plate

Optical tweezers have accelerated many advances in life science, and three-dimensional optical intensity distribution plays an important role in optical tweezers. The three-dimensional distribution of light intensity modulated by a pure phase plate is studied in this paper. Results show that the Strehl ratio can be altered by the proposed phase plate and the waist width of incident Gaussian beams. By changing geometrical parameters of the proposed phase plate, the focal depth can increase several times than that of the original system. The proposed phase plate can also be used to realize focal splitting and local minimum of intensity, which may be advantageous for constructing optical trap. And local minimum number of intensity is tunable by changing the parameters of the phase plate.