Design optimization of a metalens singlet for multimode gaussian beam shaping

In this work, we investigate the focusing efficiency and focal length dependence of a near infrared (NIR) metalens on the longitudinal and transverse modes of a Gaussian beam. We then propose a spatial multiplexing approach to design the metalens singlet optimized for mixed spectral and spatial modes. We have also made some metalens that can produce donut beam and Bessel beam.The finite difference time domain (FDTD) method is employed to simulate the designed metalens,and use photolithography to make metalens