Local Approximation-Based Simulation Method for Large-Scale Metasurfaces

To address the high computational cost and efficiency-accuracy trade-off in full-wave simulation of large-scale optical metasurfaces, this paper proposes a local approximation method. The progressive simulation scheme, based on "subdomain partitioning and boundary-condition optimization," transitions from a single meta-unit periodic subdomain to a perfectly matched layer (PML) overlapping subdomain approach. This overcomes the neglect of inter-meta-atom coupling inherent in traditional field-stitching and enhances local near-field accuracy. Validation on a one-dimensional metalens model shows that optimal agreement with full-wave simulation is achieved when both central and overlapping subdomains contain four meta atoms under PML conditions.