Topological Edge Mode Tapering

TL;DR

This paper introduces a topological bandgap engineering approach to create highly efficient, compact mode tapers in photonics, enabling scalable optical systems with minimal backscattering and mode excitation.

Contribution

It presents a novel topological bandgap engineering method for mode tapering, achieving significant mode size change in a compact device with high efficiency.

Findings

Sixfold mode width change over 8μm

Near unity efficiency in optical mode tapering

Suppressed backscattering and no higher-order mode excitation

Abstract

Mode tapering, or the gradual manipulation of the size of some mode, is a requirement for any system that aims to efficiently interface two or more subsystems of different mode sizes. While high efficiency tapers have been demonstrated, they often come at the cost of a large device footprint or challenging fabrication. Topological photonics, offering robustness to certain types of disorder as well as chirality, has proved to be a well-suited design principle for numerous applications in recent years. Here we present a new kind of mode taper realized through topological bandgap engineering. We numerically demonstrate a sixfold change in mode width over an extremely compact 8$\mu$m distance with near unity efficiency in the optical domain. With suppressed backscattering and no excitation of higher-order modes, such a taper could enable new progress in the development of scalable, multi-component systems in classical and quantum optics.