Dual-metal hybrid metasurface for liquid-tunable infrared polarization-selective perfect absorption

Abstract

Nanostructure-based metasurfaces provide a promising route for arbitrarily manipulating light waves, especially versatile absorption. Although various meta-absorbers have been studied for perfect absorption, it remains a challenge to achieve high-contrast polarization-dependent absorption with dynamic tunability. Here, a dual-metal hybrid metasurface is demonstrated for polarization-selective perfect absorption and reflection with liquid tuning capabilities in the infrared band. Based on the metal–insulator–metal architecture, the metasurface composed of Al/Ti nanostrips enables an intense absorption resonance at x-polarization and reflects light as a mirror at y-polarization, thus acting as a high-performance linear polarizer. The absorption peak wavelength can be continuously tailored from 1200 to 1850 nm with an average absorption > 99% by scaling the unit-cell period of metasurfaces. Furthermore, the perfect absorption wavelength of the metasurface exhibits a large range switch (>750 nm) through immersion tuning, and its absorption remains above 99.5%. The proposed dual-metal hybrid metasurface for liquid-tunable absorption can promote practical technologies of dynamic polarizers, photodetectors, and optical imaging.