Time-varying metasurfaces for frequency shift and bandwidth manipulation of light

Abstract

When light interacts with a medium having time-dependent optical properties, numerous optical phenomena arise that are hardly observed in static, linear, non-magnetic optical systems. Because it is challenging to implement rapid and significant variations in the optical properties with conventional bulky configurations, it would be helpful to confine light fields inside optically resonant structures such as optical resonators or waveguides. In particular, metasurface, a two-dimensional optical component consisting of an array of subwavelength scatterers, has drawn a tremendous attention as a future optical platform due to its extreme ability to control light based on the strong light-matter interaction. This dissertation proposes the use of active metasurfaces as effective time-varying media, and explores spectral manipulation techniques enabled with them. By modulating the resonance frequency or the quality factor of the metasurface rapidly over time, Doppler effect-like frequency shift and/or bandwidth manipulation of light are achievable. A feasible experimental scheme for such time-varying metasurfaces is suggested, and the efficacy is verified with numerical simulations.