Electrically tunable metasurface by using InAs in a metal–insulator–metal configuration
Junghyun Park, Seong Jun Kim, Volker J. Sorger, Soo Jin Kim
Abstract
Abstract The ability of modulating optical properties at a lateral subwavelength scale is of crucial importance due to its potential applications for wide‐angle holographic displays, optical communications, and interferometric sensors. Here, we present an electrically tunable metasurface whose optical properties can be element‐wise controlled at the lateral subwavelength scale in the mid‐infrared wavelength regime. Our proposed device facilitates an n ‐doped InAs layer as a dynamic‐tunable layer, and the charge carrier concentration inside the InAs layer is tailored by external gate biases. This InAs active layer is sandwiched between top aluminum strip antennas and a bottom gold substrate, forming the metal–insulator–metal configuration. The change of the charge carrier concentration gives rise to modulation of the amplitude and phase of reflected light in a mid‐infrared regime. Numerical investigations show the reflectivity contrast of 44%P with biases of −2.5–0 V and the phase change of 236° with biases of −15 V to +15 V at the wavelength of ∼5 μm. Versatile wavefront shaping such as beam focusing with Fresnel Zone plate and beam steering with saw‐tooth phase grating is also provided.