Tuning of Hybrid Oligomers via Nanoscale fs-Laser Reshaping

TL;DR

This paper introduces a method to precisely tune Fano resonances in hybrid Au/Si nanoparticle oligomers using femtosecond laser reshaping, enabling control over resonance wavelength and profile for nanophotonic applications.

Contribution

It presents a novel hybrid nanoparticle design with magnetic Fano resonances and demonstrates a femtosecond laser technique for fine-tuning these resonances.

Findings

Fano resonance wavelength can be shifted within 15 nm.

Laser reshaping reconfigures the resonance profile.

Hybrid oligomers exhibit sharp, tunable Fano resonances.

Abstract

Various clusters of metallic or dielectric nanoparticles can exhibit sharp Fano resonances originating from at least two modes interference of different spectral width. However, for practical applications such as biosensing or nonlinear nanophotonics, the fine-tuning of the Fano resonances is generally required. Here, we propose and demonstrate a novel type of hybrid oligomers consisting of asymmetric metal-dielectric (Au/Si) nanoparticles with a sharp Fano resonance in visible range, which has a predominantly magnetic origin. We demonstrate both, numerically and experimentally, that such hybrid nanoparticle oligomers allow fine-tuning of the Fano resonance via fs-laser induced melting of Au nanoparticles at the nanometer scale. We show that the Fano resonance wavelength can be changed by fs-laser reshaping very precisely (within 15~nm) being accompanied by a reconfiguration of its profile.