Metasurface Design Using Level-Set and Gradient Descent Optimization Techniques

Optical dielectric metasurfaces are typically composed of meta-atoms in the form of simple parametrized geometrical shapes. Meta-atoms with more complex cross-sectional geometries may enable better performance and multiple functionalities. Here we present a metasurface design technique based on a combination of the level-set method and the adjoint optimization technique that efficiently explores the available degrees of freedom of meta-atoms. As a proof of concept, we design a 75° metasurface beam deflector with 80% deflection efficiency.