Efficient second harmonic generation in a metamaterial with two resonant modes coupled through two varactor diodes

TL;DR

This paper demonstrates a method for efficient second harmonic generation using a nonlinear metamaterial with coupled resonant modes, achieving nearly 20 dB enhancement through double resonance.

Contribution

The study introduces a coupled split ring resonator design with varactor diodes enabling double resonance for enhanced SH wave generation.

Findings

19.6 dB increase in SH radiation observed

Double resonance significantly improves SH efficiency

Effective method for nonlinear metamaterial design

Abstract

We present an effective method to generate second harmonic (SH) waves using nonlinear metamaterial composed of coupled split ring resonators (CSRRs) with varactor (variable capacitance) diodes. The CSRR structure has two resonant modes: a symmetric mode that resonates at the fundamental frequency and an anti-symmetric mode that resonates at the SH frequency. Resonant fundamental waves in the symmetric mode generate resonant SH waves in the anti-symmetric mode. The double resonance contributes to effective SH radiation. In the experiment, we observe 19.6 dB enhancement in the SH radiation in comparison with the nonlinear metamaterial that resonates only for the fundamental waves.