Theory of pump-probe experiments of metallic metamaterials coupled to the gain medium

TL;DR

This paper introduces a new simulation approach for pump-probe experiments involving metallic metamaterials coupled with gain media, revealing unexpected negative differential transmittance and aiding in loss compensation design.

Contribution

It develops a novel simulation method for pump-probe experiments with metallic metamaterials and gain media, providing insights into their coupling mechanisms and experimental design.

Findings

Negative differential transmittance observed for SRRs on gain substrate

Simulation results align with experimental data

Potential for designing loss-compensated metamaterials

Abstract

We establish a new approach for pump-probe simulations of metallic metamaterials coupled to the gain materials. It is of vital importance to understand the mechanism of the coupling of metamaterials with the gain medium. Using a four-level gain system, we have studied light amplification of arrays of metallic split-ring resonators (SRRs) with a gain layer underneath. We find that that the differential transmittance \Delta T/T can be negative for SRRs on the top of the gain substrate, which is not expected, and \Delta T/T is positive for the gain substrate alone. These simulations agree with pump-probe experiments and can help to design new experiments to compensate the losses of metamaterials.