Optimization of broadband, polarization-independent metasurface using gradient-based inverse design

In recent decades, metasurface have been interested to seek the possibilities of replacing conventional optics such as lens, mirror, and antenna. However, it was quite time-intensive task to design meta-atoms of desired optical properties with traditional design methods, which initialize first and then conducting parametric sweeping for analyzing the structure. Here, we adopted the adaptive moment estimation optimization algorithm to inverse-design the meta-atoms which show similar cross-polarization efficiencies in the broadband visible light region (450nm–650nm). Furthermore, thanks to the metaatoms which utilizes Pancharatnam-Berry phase, we simply obtained the phase-delayed meta-atoms of out-of-phase condition without further calculations. Our future works of integrating every meta-atom into a meta-lens which shows broadband high transmission efficiencies with dispersion-limited behavior.