Mie-resonant semiconductor metasurfaces beyond wavefront control

High-refractive-index dielectric nanoresonators support multipolar Mie-type resonances while exhibiting very low absorption losses at optical frequencies. These resonances can be tuned via the size, shape, material composition, and environment of the nanoresonators using the capabilities of modern nanotechnology. Thus, carefully designed dielectric nanoresonatos can be arranged in a planar fashion to form resonant metasurfaces with tailored linear and nonlinear optical properties.
This talk will review our recent advances in controlling the generation and propagation of light with metasurfaces composed of Mie-resonant semiconductor nanoparticles. Such metasurfaces can impose a spatially variant phase shift onto an incident light field, thereby providing control over its wavefront. Low absorption losses and impedance matching by simultaneous excitation of electric and magnetic dipolar Mie-type resonances allow for metasurfaces with high transmission efficiency.

However, there are two important limitations: The majority of semiconductor metasurfaces realized so far are passive, i.e. they require an external light source to synthesize a desired light field. Secondly, they are usually static, i.e. their optical response becomes permanently encoded into the structure during fabrication. This talk will concentrate on strategies to integrate emitters into the metasurfaces and to obtain dynamic control of the metasurface optical response.

Two approaches for active tuning of the metasurface response will be discussed, namely integration of the metasurface into a nematic-liquid-crystal cell and ultrafast all-optical tuning based on the nonlinear optical response of the constituent semiconductor materials. Furthermore, I will show that Mie-resonant semiconductor metasurfaces allow for spatial and spectral tailoring of spontaneous emission from various types of emitters.