Polarization-optimized metasurface Fresnel zone plate for on-axis intensity redistribution

Fresnel zone plates (FZPs) can achieve constructive interference at the center of the focal plane. However, it is unsolved to realize extended depth of focus (DOF) and multiple focal spots utilizing the optimized polarization distribution while the incident field and the classical FZP's phase distribution are unchanged. Here, we propose the polarization-optimized metasurface Fresnel zone plate (POMFZP) to convert the incident linearly polarized beam to the beam with the optimized polarization distribution and to focus the latter to approximate the predefined on-axis intensity distribution. The focusing characteristics of two designed POMFZPs are numerically demonstrated. The first POMFZP focuses the incident plane wave into a diffraction-limited focal spot with the extended DOF. The second POMFZP focuses the incident plane wave into two solid diffraction-limited focal spots on the z-axis. Therefore, we believe that our method can provide ideas to realize the vector holography and complex vector field.