Robust transport of high-speed data in a topological valley Hall insulator

Photonic topological insulators provide robust transport of light, enabling interesting phenomena such as unidirectional light propagation and immunity to disorder. The discovery of how to effectively break time reversal symmetry was an important development in the field of photonic topological insulators. Knowledge on how to implement designs in all-dielectric systems was an especially crucial development, enabling complementary metal-oxide semiconductor-based materials and processes to be used to study such structures, accelerating their pace of innovation. On the other hand, transmission of high-speed data is of fundamental importance in communications systems prolific in data centers and telecommunications. In this paper, we demonstrate robust transport of high-speed non-return-to-zero (NRZ) and pulse amplitude modulation 4 (PAM4) in a photonic topological insulator based on the quantum valley Hall effect. The structure utilizes a Kagome lattice with a slightly broken symmetry to achieve a domain wall between two regions with half-integer valley Chern numbers. The topological structure's immunity to backscattering allows high-speed data to be transmission through a zigzag path with four 120° bends. Characterization of reference devices including a trivial device and photonic waveguide device shows that the topological device is superior in the robust transport of high-speed data, enabling a low BER of 10^-8 for 30 Gbps NRZ data and an open eye observed for 100 Gbps PAM4 data even when transmitted through a zigzag optical path.