Tuning of magnetic optical response in a dielectric nanoparticle by ultrafast photo-injection of dense electron-hole plasma

TL;DR

This paper introduces a method to rapidly tune the optical response of a dielectric nanoparticle using femtosecond laser pulses that inject dense electron-hole plasma, significantly altering its scattering properties.

Contribution

It presents a novel ultrafast tuning technique for magnetic optical responses in high-index nanoparticles via photo-injection of dense electron-hole plasma.

Findings

Achieved 20% reflectance tuning of a silicon nanoparticle.

Demonstrated control over electric and magnetic scattering responses.

Enabled potential for ultrafast optical switching devices.

Abstract

We propose a novel approach for efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation. This concept is based on ultrafast photo-injection of dense (>10^20 cm^-3) electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows to manipulate by both electric and magnetic nanoparticle responses, resulting in dramatic changes of its scattering diagram and scattering cross section. We experimentally demonstrate 20 % tuning of reflectance of a single silicon nanoparticle by femtosecond laser pulses with wavelength in the vicinity of the magnetic dipole resonance. Such single-particle nanodevice enables to design fast and ultracompact optical switchers and modulators.