Structural Control of Metamaterial Oscillator Strength and Electric Field Enhancement at Terahertz Frequencies

TL;DR

This paper demonstrates a structural method to control oscillator strength and electric field enhancement in terahertz metamaterials by shifting resonator arrays, confirmed through experiments and simulations.

Contribution

It introduces a design approach for tunable oscillator strength and electric field enhancement in terahertz metamaterials via lateral shifting of resonator arrays.

Findings

Oscillator strength decreased by a factor of 4 with shift.

Electric field enhancement amplitude changed by 40%.

Results confirmed by terahertz spectroscopy and simulations.

Abstract

The design of artificial nonlinear materials requires control over the internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists of a split ring resonator (SRR) array stacked above an array of nonresonant closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in a decrease of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field enhancement in the SRR capacitive gap. We use terahertz time-domain spectroscopy and numerical simulations to confirm our results and we propose a qualitative inductive coupling model to explain the observed electromagnetic reponse.