Tunable Metasurfaces in III-V Materials—Design and Experiment

We investigate the design of tunable metasurfaces using III-V materials as the insulator layer in metal-insulator-metal (MIM) designs. We first propose several designs for switchable and tuanble thermal emissivity in such structures. We consider the use of incorporated p-i-n junctions to tune the carrier concentration, and hence the refractive index, of the III-V structure. In one case, we introduce a perturbation to every other tooth of an MIM grating, doubling the effective periodicity. We show that this effect opens a photonic band gap, switching off the emissivity at the desired midwave infrared wavelength. In a second approach, we investigate index tuning in a slow light structure. Here, the slow light design magnifies the angular sensitivity with respect to index change. We further present our experimental progress toward such structures. In a first case, we demonstrate direct growth of InAs on a metallic substrate for realization of midwave infrared metamaterials. In a second case, we investigate epitaxial gransfer of GaAs on a metallic substrate for the same purpose.