Structuring band-pass dispersion with cascaded high- and low-pass optical metatronic metasurfaces

In the paradigm of optical metatronics, metasurfaces with multi-layered structures can be engineered to behave as multi-ordered filters for desired spectral dispersions, such as low-pass, high-pass, band-pass, and band-stop cases, following and inspired by electronic circuit design procedures. However, there is a constraint in the design of layered band-pass metatronic filters with narrow bandwidth. Based on the concept of metatronic metasurfaces, a new method is proposed to achieve optical band-pass dispersion by cascading a pair of metatronic high-pass and low-pass metasurface filters. The proposed method is also numerically validated in the higher-ordered band-pass filter design with sharper transition slopes to the stopband. The results of our numerical simulations illustrate the possibility for such multi-ordered optical band-pass filters with narrow bandwidth, augmenting the procedures for dispersion engineering using layered metatronic metasurfaces.