Sum-Frequency and Second-Harmonic Generation from Plasmonic Nonlinear Nanoantennas

TL;DR

This paper models second-order nonlinear optical processes like sum-frequency and second-harmonic generation in plasmonic nanoantennas using boundary element method, validating results with Mie theory and exploring design enhancements.

Contribution

It introduces a boundary element method-based nonlinear solver for plasmonic nanoantennas, enabling accurate analysis and guiding design of enhanced nonlinear optical devices.

Findings

Enhanced nonlinear signals due to double-resonance and gap plasmonic modes.

Unidirectional nonlinear radiation achieved from PIC-NA.

Emission direction controllable by nanosphere position.

Abstract

Plasmonic nanostructures that support surface plasmon (SP) resonance potentially provide a route for the development of nanoengineered nonlinear optical devices. In this work, second-order nonlinear light scattering, specifically sum-frequency generation (SFG) and second-harmonic generation (SHG), from plasmonic nanoantennas is modeled by the boundary element method (BEM). Far-field scattering patterns are compared with the results calculated by the Mie theory to validate the accuracy of the developed nonlinear solver. The SFG from a multi-resonant nanoantenna (MR-NA) and the SHG from a particle-in-cavity nanoantenna (PIC-NA) are analyzed by using the developed method. Enhancements of the scattering signals due to double-resonance of the MR-NA and gap plasmonic mode of the PIC-NA are observed. Unidirectional nonlinear radiation for the PIC-NA is realized. Moreover, its emission direction can be controlled by the location of the nanosphere. This work provides new theoretical tools and design guidelines for plasmonic nonlinear nanoantennas.