Robust inverse design of all-dielectric metasurface transmission-mode color filters

Abstract

The strong dispersion, ultra-thin form-factor and robustness to degradation make metasurfaces attractive for color filter applications. In particular, transmission-mode filters using silicon could potentially replace conventional color filter arrays in backside-illuminated CMOS image sensors and enable novel multispectral image sensors. We report a robust inverse-design methodology using polygon-shaped, particle and void, meta-atoms. We predict that silicon metasurface transmission-mode primary color (RGB) filters designed with this approach exhibit enhanced color gamut, color purity and intra-pixel color uniformity in comparison to previous reports. The proposed robust inverse design procedure employs multi-island Differential Evolution whose fitness evaluation step uses a statistical model of nanofabrication imperfections. The statistical model can closely recreate the shape variations observed in micrographs of silicon metasurfaces fabricated using electron-beam lithography and is useful in guiding the optimization process towards robust designs.

Dielectric Mie voids: confining light in air

“…While a similar phenomenon is known for metallic structures by virtue of Babinet’s principle 37 – 39 , in dielectric systems the full strength of this symmetry has not been explored or experimentally implemented. Optical resonances in textured, semi-periodic dielectric void systems of corrugated silicon surfaces have been studied and resonances associated with voids have been found, which were utilized for absorption enhancement 40 as well as light manipulation 41 . In nanoporous, periodic gold surfaces void-based resonances were found, which are interpreted as combinations of Mie void resonances and plasmonic phenomena due to the presence of the metall 42 , 43 .…”

Empowering Metasurfaces with Inverse Design: Principles and Applications

“…Other evolutionary algorithms have also been developed for metasurface inverse design including a simulated annealing method for the design of binary plasmonic structures that engineer surface plasmon polaritons, A branch-and-bound method for a true global optimization of thin-film optical filter design, a multi-island differential evolution for a metasurface color filter design, and a Bayesian optimization method to search for a global optimal design of phase gradient metasurfaces, etc.…”

Deep learning aids simultaneous structure–material design discovery: a case study on designing phase change material metasurfaces

“…The CST EM-solver was used for obtaining the optical response with the unit-cell boundary in the x and y directions and the open boundary in the z direction. A more detailed set of CST settings can be found in our previous work 24 . Switching between the resonance state (such as the electric dipole 69 and magnetic dipole 69 modes) and a non-resonant state offers high switching contrasts at that wavelength.…”

“…Therefore, there is an increasing demand for the exploration of geometries that are within reach of nanofabrication. The recent repertoire has showcased complex multi-variable metasurface designs in the shape of polygon meta-atoms, 22 – 25 free-form geometries, 26 – 30 extended meta-atoms, 31 , 32 and volumetric structures 33 . Approaches for simultaneous design discovery in structure–material design space remain largely unexplored.…”

“…A more detailed set of CST settings can be found in our previous work. 24 Switching between the resonance state (such as the electric dipole 69 and magnetic dipole 69 modes) and a non-resonant state offers high switching contrasts at that wavelength. Corresponding to Figs.…”