Topology optimization of freeform large-area metasurfaces

Abstract

We demonstrate optimization of optical metasurfaces over $10^5$--$10^6$ degrees of freedom in two and three dimensions, 100--1000+ wavelengths ($\lambda$) in diameter, with 100+ parameters per ${\lambda }^2$. In particular, we show how topology optimization, with one degree of freedom per high-resolution "pixel," can be extended to large areas with the help of a locally periodic approximation that was previously only used for a few parameters per ${\lambda }^2$. In this way, we can computationally discover completely unexpected metasurface designs for challenging multi-frequency, multi-angle problems, including designs for fully coupled multi-layer structures with arbitrary per-layer patterns. Unlike typical metasurface designs based on subwavelength unit cells, our approach can discover both sub- and supra-wavelength patterns and can obtain both the near and far fields.

References in corpus (3)

• Multiwavelength Achromatic Metasurfaces by Dispersive Phase Compensation
• Electromagnetic Wave Source Conditions
• Photon Torpedoes and Rytov Pinwheels: Integral-Equation Modeling of Non-Equilibrium Fluctuation-Induced Forces and Torques on Nanoparticles

Cited by in corpus (1)

• Tunable metasurface inverse design for 80% switching efficiencies and 144${}^{\circ }$ angular steering