Gate-tunable optical filter based on conducting oxide metasurface heterostructure.

A gate-tunable plasmonic optical filter incorporating a subwavelength patterned metal-insulator-metal metasurface heterostructure is proposed. An additional thin transparent conducting oxide (TCO) layer is embedded in the insulator layer to form a double metal-oxide-semiconductor configuration. Heavily n-doped indium tin oxide (ITO) is employed as the TCO material, whose optical property can be electrically tuned by the formation of a thin active epsilon-near-zero layer at the ITO-oxide interfaces. Full-wave electromagnetic simulations show that amplitude modulation and shift of transmission peak are achievable with 3-5 V applied bias, depending on the application. Moreover, the modulation strength and transmission peak shift increase with a thinner ITO layer. This work is an essential step toward a realization of next-generation compact photonic/plasmonic integrated devices.