Laser beam homogenization and shaping with metasurfaces

All-dielectric metalens based on the transmission phase was designed, which can uniformly shape a beam with a uniform energy distribution. The problems and related fixes for maintaining beam homogeneity and broad divergence angle simultaneously at 940 nm are explained. In order to solve the problem of wavefront shaping, based on the iterative design principle of complex surfaces such as freeform surfaces, a design scheme to shape the incident wavefront into 80° divergence angle wavefront was proposed. An effective, polarization-independent silicon nanopillar element is built based on the effective dielectric theory, and instead of using the conventional step size selection method, the size of each nanopillar is determined by the phase diameter function, covering the phase tuning from 0 to 2π.