Parametric Mie Resonances and Directional Amplification in Time-Modulated Scatterers
Viktar Asadchy, Aristeidis Lamprianidis, Grigorii Ptitcyn, Mohammad Albooyeh, Rituraj Rituraj, Theodosios D. Karamanos, Rasoul Alaee, Sergei Tretyakov, Carsten Rockstuhl, Shanhui Fan
Abstract
We provide a theoretical description of light scattering by a spherical particle the permittivity of which is modulated in time at twice the frequency of the incident light. Such a particle acts as a finite-sized photonic time crystal and, despite its subwavelength spatial extent, can host optical parametric amplification. Conditions of parametric Mie resonances in the sphere are derived. We show that time-modulated materials provide a route to tailor directional light amplification, qualitatively different from that in scatterers made from a gain media. We design two characteristic time-modulated spheres that simultaneously exhibit light amplification and desired radiation patterns, including those with zero backward and/or vanishing forward scattering. The latter sphere provides an opportunity for creating shadow-free detectors of incident light.