Resonant Meta-atoms with Nonlinearities on Demand

TL;DR

This paper introduces a doubly resonant nonlinear meta-atom with a shared varactor diode, enabling precise control of nonlinear harmonic generation in the GHz range for advanced photonic applications.

Contribution

It presents a novel design of a doubly resonant meta-atom with tunable nonlinear harmonic efficiencies, advancing control over nonlinear light-matter interactions.

Findings

Enhanced control over second and third harmonic generation.

Flexible tuning of coupling and radiation patterns.

Guidelines for selecting harmonic frequencies based on geometry.

Abstract

Nonlinear light-matter interactions and their applications are constrained by properties of available materials. The use of metamaterials opens the way to achieve precise control over electromagnetic properties at a microscopic level, providing new tools for experimental studies of complex nonlinear phenomena in photonics. Here a doubly resonant nonlinear meta-atom is proposed, analyzed and characterized in the GHz spectral range. The underlying structure is composed of a pair of split rings, resonant at both fundamental and nonlinear frequencies. The rings share a varactor diode, which serves as a microscopic source of nonlinearity. Flexible control over the coupling and near- and far-field patterns are reported, favoring the doubly resonant structure over other realizations. Relative efficiencies of the second and third harmonics, generated by the diode, are tailored by dint of the double-ring geometry, providing a guideline for selecting one frequency against another, using the design of the auxiliary structures. The on-demand control over the microscopic nonlinear properties enables developing a toolbox for experimental emulation of complex nonlinear phenomena.