Optimization of metasurface design curves using the grating averaging technique

We present a technique for designing efficient and robust metasurfaces that optimizes the metasurface design curves instead of individual metasurface elements and thus does not suffer from the size limitations of conventional optimization techniques. Spatially varying design curves are parametrized and optimized using the grating averaging technique. We present simulation and experimental results of highly efficient metasurface beam deflectors and lenses that are robust to fabrication errors. In particular, we present an 80° beam deflector with absolute efficiency of 75% and a metalens with NA of 0.8 and an efficiency of 86% that is robust to fabrication errors.