Adjoint inverse-design of polarization-dependent Mie-resonant lenses

Polarization-dependent dielectric lenses based on Mie resonances offer a low-loss alternative for wavefront transformations. However, designing such structures for arbitrary steering capabilities remains computationally challenging due to the large number of design variables. An inverse-design methodology for a Mie-resonant dielectric lens using an adjoint optimization framework is validated for realizing arbitrary beam steering. To enable polarization-dependence, the proposed approach first exploits the anisotropic refractive index of a cuboid-shaped BaxSr1−xTiO3 (BST) meta-atom. The refractive indices for transverse electric and transverse magnetic polarizations are then simultaneously incorporated into the inverse-design framework to determine the optimal spatial distribution of identical BST meta-atoms for prescribed polarization-dependent beam manipulations. The versatility of the proposed framework is numerically validated through representative examples of beam collimation and steering, which demonstrate the capability to rapidly design polarization-dependent Mie-resonant dielectric lenses.