Topologically protected power divider and wavelength division multiplexer based on valley photonic crystals

Topological photonic crystals are known for their topologically protected edge states, enabling robust and low-loss transmission even in the presence of structural defects or sharp bends. In this study, what we believe to be a novel valley photonic crystal is fabricated and the transition structure interconnecting it with the traditional coplanar waveguide is meticulously designed, successfully realizing efficient coupling between the two. Then, based on the characteristics of topological photonic crystals, a topological power divider is designed. Within the frequency range of 5.44 GHz to 6.2 GHz, a 1:1 power splitting is successfully achieved, demonstrating strong robustness and stable transmission performance under complex transmission conditions. In addition, by adjusting the frequency of the topological edge states, a topological photonic crystal wavelength division multiplexer is successfully designed. The wavelength division multiplexer is configured with two distinct channels (the first channel covers the frequency range from 5.8 GHz to 6.02 GHz, while the second one spans from 6.06 GHz to 6.22 GHz), achieving the function of wavelength division multiplexing. The devices designed in this study provide what we believe to be new ideas and methods for achieving high-performance, low-loss microwave transmission and integrated photonic devices.