All-optical radiofrequency modulation of Anderson-localized modes

TL;DR

This paper demonstrates all-optical modulation of Anderson-localized modes in disordered photonic/phononic crystal waveguides with high Q-factors, enabling low-power nonlinear effects and dynamic control of resonant wavelengths.

Contribution

It introduces a system with high-Q Anderson-localized modes that exhibit nonlinear oscillations at low excitation powers, advancing disordered photonics control.

Findings

Achieved Q-factors up to 10^5 in disordered waveguides.

Observed nonlinear wavelength oscillations up to 35 MHz at below 1 mW power.

Showcased potential for dynamic optical control in disordered photonic systems.

Abstract

All-optical modulation of light relies on exploiting intrinsic material nonlinearities. However, this optical control is rather challenging due to the weak dependence of the refractive index and absorption coefficients on the concentration of free carriers in standard semiconductors. To overcome this limitation, resonant structures with high spatial and spectral confinement are carefully designed to enhance the stored electromagnetic energy, thereby requiring lower excitation power to achieve significant nonlinear effects. Small mode-volume and high quality (Q)-factor cavities also offer an efficient coherent control of the light field and the targeted optical properties. Here, we report on optical resonances reaching Q - 10^5 induced by disorder on novel photonic/phononic crystal waveguides. At relatively low excitation powers (below 1 mW), these cavities exhibit nonlinear effects leading to periodic (up to - 35 MHz) oscillations of their resonant wavelength. Our system represents a test-bed to study the interplay between structural complexity and material nonlinearities and their impact on localization phenomena and introduces a novel functionality to the toolset of disordered photonics.