Nonlinear heating and scattering in a single crystalline silicon nanostructure

Area of Science:

• Photonics
• Nanotechnology
• Materials Science

Background:

• Silicon nanophotonics offers efficient light confinement but suffers from weak optical nonlinearity, hindering applications like all-optical switches.
• Mie resonance in silicon nanostructures can enhance optical effects.
• Understanding nonlinear optical properties is crucial for advancing silicon photonics.

Purpose of the Study:

• To experimentally demonstrate and analyze the nonlinear heating of silicon nanostructures.
• To establish the connection between nonlinear scattering and nonlinear heating.
• To provide a quantitative model for photo-thermo-optic properties in silicon nanostructures.

Main Methods:

• In situ Raman spectroscopy was used to measure temperature rise in a silicon nanoblock.
• Finite-element simulations were employed to model the photo-thermo-optic effect.
• Analysis focused on the coupled red shift of scattering and absorption spectra.

Main Results:

• A giant nonlinearity in heating was observed in silicon nanostructures, correlating with nonlinear scattering.
• Experimental results align with finite-element simulations based on the photo-thermo-optic effect.
• The nonlinear effect is attributed to the coupled consequence of spectral shifts in scattering and absorption.

Conclusions:

• This study unravels nonlinear absorption mechanisms in silicon Mie-resonators.
• A quantitative analytic model for silicon nanostructure photo-thermo-optic properties was developed.
• The findings offer new perspectives for practical silicon photonics applications, particularly in all-optical switching.