Reversible modulation and ultrafast dynamics of THz resonances in strongly photoexcited metamaterials

TL;DR

This paper demonstrates ultrafast reversible control of terahertz resonances in photoexcited metamaterials, revealing complex transient behaviors and proposing a new approach for nonlinear THz modulation.

Contribution

It introduces a novel method for ultrafast reversible modulation of THz responses in metamaterials, supported by simulations that incorporate transient diffraction effects.

Findings

Non-monotonic spectral response as a function of pump fluence

Re-emergence of resonances after initial quenching

Simulation reproduces key experimental features

Abstract

We demonstrate an ultrafast reversible modulation of resonant terahertz (THz) response in strongly photoexcited metamaterials. The transient spectral-temporal response of the dipole transition ~1.6 THz exhibits a distinct non-monotonic variation as a function of pump fluence. The transition energy shift, strength, spectral width and density-dependent ultrafast relaxation manifest a remarkable re-emergence of the resonances after initial quenching. Our simulation, incorporating the first-order diffraction from the photoinduced transient grating, reproduces the salient features, providing a new avenue for designing nonlinear and frequency-agile THz modulators.