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All-Dielectric Active Metasurfaces Based on Electro-Optic Effect in III-V Multiple-Quantum-Well Resonators

Nature Communications
Tunable metasurfaces enable dynamical control of key constitutive properties of light at a subwavelength scale. So far, electrically-tunable active metasurfaces at near-infrared wavelengths have been typically achieved by incorporating active materials into otherwise passive metasurface structures. To achieve a significant tunable response in these hybrid active material-metasurface structures, a strong field enhancement in the active material is necessary creating significant design and fabrication challenges. Here, we report an all-dielectric active metasurface platform based on electro-optically tunable III-V multiple-quantum-wells (MQWs). Our MQWs are patterned into subwavelength metasurface elements such that each metasurface element supports a hybrid Mie-guided mode (Mie-GM) resonance. We utilize the quantum-confined Stark effect in the MQW to actively control the optical response of the metasurface in the near-infrared (NIR) wavelength range. By applying a DC electric field across the dielectric resonators, we actively modulate the properties of the volumetric Mie-GM resonance supported by the metasurface elements. We experimentally observe a relative reflectance modulation of 270% accompanied with a continuous phase shift from 0° to ~70°. In addition, we use our all-dielectric tunable metasurface to demonstrate beam steering. The beam steering is achieved by individually applying an electrical bias to each metasurface element and thus actively changing the period of the metasurface. The proposed metasurface platform can be used for the realization of dynamically tunable ultrathin optical components, such as tunable metalenses, on-chip beam steering devices, active polarizers, and flat spatial light modulators.
Nature Comm. 10, 3654 (2019)