Harnessing the natural resonances of time-varying dispersive interfaces

TL;DR

This paper investigates wave scattering at a time-varying dispersive interface, revealing a new frequency generation process at natural resonances that enables direct excitation of surface waves, promising advances in ultrafast photonic device design.

Contribution

It introduces a novel phenomenon of frequency generation at natural resonances in time-varying dispersive interfaces, enabling direct surface wave excitation without spatial gratings.

Findings

Discovery of unconventional frequency generation at natural resonances.

Coupling of propagating waves to evanescent surface waves.

Potential for designing compact, ultrafast photonic devices.

Abstract

Space-time modulation of electromagnetic parameters offers novel exciting possibilities for advanced field manipulations. In this study, we explore wave scattering from a time-varying interface characterized by a Lorentz-type dispersion with a step-like temporal variation in its parameters. Our findings reveal a new process: an unconventional frequency generation at the natural resonances of the system. Remarkably, this phenomenon enables the coupling of propagating waves to evanescent ones, allowing the direct far-field excitation of surface-wave modes without the mediation of spatial gratings or prisms. These results suggest a novel strategy for designing compact and ultra-fast photonic devices, eliminating the necessity for subwavelength spatial structuring or prolonged temporal modulations.