Anapoles in Free-Standing III-V Nanodisks Enhancing Second-Harmonic Generation

TL;DR

This paper introduces a novel method for creating free-standing III-V nanodisks with anapole configurations that suppress radiation and significantly enhance second-harmonic generation, advancing nanophotonic device design.

Contribution

It presents a new approach to fabricate nonradiating nanodisks from nanowires using focused ion beam milling, demonstrating enhanced nonlinear optical effects.

Findings

Suppression of far-field radiation in nanodisks

Strong enhancement of second-harmonic generation

Confirmation of anapole (nonradiating) configurations via multipole analysis

Abstract

Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, where a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to create nanoantennas by slicing III-V nanowires into standing disks using focused ion beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure to design and produce disk nanoantennas from nanowires become one of standard approaches to fabricate controlled chains of standing nanodisks with different designs and configurations. These chains can be an essential building blocks for new types of lasers and sensors with low power consumption.