Nonlinear Transient Dynamics of Photoexcited Silicon Nanoantenna for Ultrafast All-Optical Signal Processing

TL;DR

This paper demonstrates ultrafast optical plasma generation in silicon nanoparticles, enabling sub-100 femtosecond all-optical switching and paving the way for ultracompact, ultrafast optical signal processing devices.

Contribution

It provides experimental evidence and an analytical model of ultrafast plasma-driven nonlinear response in silicon nanostructures for optical switching.

Findings

Ultrafast (2.5 ps) relaxation of optically generated plasma in silicon nanoparticles.

Demonstration of 100 fs unidirectional scattering switching.

Development of an analytical model for transient optical response.

Abstract

Optically generated electron-hole plasma in high-index dielectric nanostructures was demonstrated as a means of tuning of their optical properties. However, until now an ultrafast operation regime of such plasma driven nanostructures has not been attained. Here, we perform pump-probe experiments with resonant silicon nanoparticles and report on dense optical plasma generation near the magnetic dipole resonance with ultrafast (about 2.5 ps) relaxation rate. Basing on experimental results, we develop an analytical model describing transient response of a nanocrystalline silicon nanoparticle to an intense laser pulse and show theoretically that plasma induced optical nonlinearity leads to ultrafast reconfiguration of the scattering power pattern. We demonstrate 100 fs switching to unidirectional scattering regime upon irradiation of the nanoparticle by an intense femtosecond pulse. Our work lays the foundation for developing ultracompact and ultrafast all-optical signal processing devices.