Reducing Disorder-Induced Backscattering in Photonic Crystal Waveguides through Inverse Design

TL;DR

This paper introduces an inverse design methodology that significantly reduces disorder-induced backscattering in photonic crystal waveguides, enhancing their performance for nanophotonics applications.

Contribution

It presents a novel inverse design approach combining mode solving and physics-based scattering formulas to minimize backscattering losses in 3D photonic crystal waveguides.

Findings

Backscattering losses are significantly reduced using the proposed design method.

Improvements are demonstrated for both W1-like and topological waveguide modes.

The methodology is fully three-dimensional and adaptable to various design metrics.

Abstract

Photonic crystal waveguides (PCWs) allow for the engineering of photonic modes and band structures to control the flow of light and light-matter interactions within the waveguide. They have shown potential for enhancing optical nonlinearities, quantum dot single photon emissions, as well as optical buffers due to their ability to confine fields on-chip and produce slow-light modes. While these features are promising for applications in nanophotonics, PCWs are prone to high scattering losses due to disorder-induced backscattering, which has remained a significant problem for decades, across various waveguide designs. By combining a fast mode solving approach with physics-based scattering formulas and inverse design, we show how backscattering losses can be significantly reduced, even when working at the same group index. We demonstrate substantial improvements for both W1-like waveguide modes as well topological waveguide modes. Our general methodology is fully three dimensional and can be used to introduce new PCWs for a variety of design metrics.