Title: Rapid Design of Wide-Area Heterogeneous Electromagnetic Metasurfaces beyond the Unit-Cell Approximation,
Abstract: We propose a novel numerical approach for the optimal design of wide-area
heterogeneous electromagnetic metasurfaces beyond the conventionally used
unit-cell approximation. The proposed method exploits the combination of
Rigorous Coupled Wave Analysis (RCWA) and global optimization techniques (two
evolutionary algorithms namely the Genetic Algorithm (GA) and a modified form
of the Artificial Bee Colony (ABC with memetic search phase method) are
considered). As a specific example, we consider the design of beam deflectors
using all-dielectric nanoantennae for operation in the visible wavelength
region; beam deflectors can serve as building blocks for other more complicated
devices like metalenses. Compared to previous reports using local optimization
approaches our approach improves device efficiency; transmission efficiency is
especially improved for wide deflection angle beam deflectors. The ABC method
with memetic search phase is also an improvement over the more commonly used GA
as it reaches similar efficiency levels with upto 35% reduction in computation
time. The method described here is of interest for the rapid design of a wide
variety of electromagnetic metasurfaces irrespective of their operational
wavelength.