Super-robust telecommunications enabled by topological half-supermodes

TL;DR

This paper introduces topological half-supermodes in valley-ridge gap waveguides, enabling ultra-compact, backscattering-immune integrated waveguides with seamless standard mode matching and demonstrated low reflection losses in telecom scenarios.

Contribution

It presents a novel valley-ridge gap waveguide design that harnesses topological half-supermodes for robust, ultra-compact, and seamlessly integrated photonic devices.

Findings

Reflection losses lower than -15 dB in telecom scenarios

Successful demonstration of backscattering-immune propagation through sharp bends

Achieved mode matching with standard waveguides without transition structures

Abstract

Topological photonics offers transformative potential for robust integrated waveguide devices due to their backscattering-immune properties. However, their integration faces two fundamental challenges: mode symmetry mismatch with conventional waveguides and prohibitive dimensions. We successfully overcome these two critical challenges by introducing a novel valley-ridge gap waveguide based on topological half-supermode engineering. By strategically hybridizing ridge waveguide modes and valley kink states, we create an exotic odd-symmetric supermode enabling robust propagation and ultra-compact operation. The further implementation of a perfect electric conductor boundary halves lateral dimensions while eliminating radiation loss. Crucially, our proposed valley-ridge interface achieves direct transverse electric mode matching with standard waveguides without transition structures, enabling seamless integration. Experimental results demonstrate reflection losses lower than -15 dB in realistic telecommunication scenarios with super-robust signal propagation through sharp bends. This work innovatively conceptualizes topological half-supermodes and pioneers their practical applications for integrated waveguide devices, establishing a completely new waveguide class that uniquely combines robust backscattering immunity with deep subwavelength compactness.