Tunable directional filter for mid-infrared optical transmission switching

Abstract

Controlling the spectral and angular response of infrared (IR) radiation is a challenging task of paramount importance to various emerging photonic applications. Here, we overcome these problems by proposing and analyzing a new design of a tunable narrowband directional optical transmission filter. The presented thermally controlled multilayer filter leverages the temperature dependent phase change properties of vanadium dioxide (VO2) to enable efficient and reversible fast optical switching by using a pump-probe laser excitation setup. More specifically, transmission is blocked for high intensity probe lasers due to the VO2 metallic properties induced at elevated temperatures while at low probe laser intensities high transmission through the filter occurs only for a narrowband IR range confined to near normal incident angles. The proposed multilayer composite dielectric filter is expected to have applications in optical communications, where it can act as dual functional infrared filter and optical switch.

Exceptional points in parity-time symmetric plasmonic Huygens’ metasurfaces

“…To sum up, the reflectionless transmission obtained at the EP will enable the use of the proposed active core-shell array metasurface to be employed as a compact nanophotonic optical filter with perfect transmission. Compared to other conventional multilayer optical filter designs [36][37][38][39], the proposed metasurface is extremely thin, making its fabrication and implementation much simpler and cost effective.…”

“…We further analyze the EP singularity by demonstrating the eigenvalue switching behavior when encircling the EP in the complex frequency space. The proposed non-Hermitian PTsymmetric ultrathin metasurface design is expected to have applications in compact perfect transmission optical filtering, since its thickness is extremely smaller compared to conventional multilayer filters based on low loss dielectric materials [36][37][38][39].…”