Demonstration of a plasmonic nonlinear pseudo-diode

TL;DR

This paper demonstrates a nonlinear plasmonic metasurface that acts like a diode for second-harmonic generation, showing strong asymmetric nonlinear scattering with about 10 dB extinction ratio, confirmed by experiments and simulations.

Contribution

It introduces a novel nonlinear plasmonic metasurface with asymmetric SHG response enabled by material composition asymmetry and bianisotropic effects.

Findings

Achieved approximately 10 dB extinction ratio in SHG between opposite excitation directions.

Confirmed the bianisotropic response through homogenization analysis and susceptibility tensor extraction.

Demonstrated diode-like nonlinear behavior in a plasmonic metasurface.

Abstract

We demonstrate a nonlinear plasmonic metasurface that exhibits strongly asymmetric second-harmonic generation: nonlinear scattering is efficient upon excitation in one direction and it is substantially suppressed when the excitation direction is reversed, thus enabling a diode-like functionality. A significant (approximately 10 dB) extinction ratio of SHG upon opposite excitations is measured experimentally and those findings are substantiated with full-wave simulations. The combination of two commonly used metals - aluminium and silver - produces a material composition asymmetry that results into a bianisotropic response of the system, as confirmed by performing homogenization analysis and extracting an effective susceptibility tensor. Finally, we discuss the implications of our results from the more fundamental perspectives of reciprocity and time-reversal asymmetry.