Design and Numerical Demonstration of All-Optical Logic Devices Based on Topological Valley Photonic Crystals with Circular Ring Dielectric Columns

One of the bottlenecks in realizing all-optical computing is the lack of on-chip all-optical logic devices that combine compact, low-loss, and highly robustness. Valley photonic crystals (VPCs) have become an important solution for realizing such devices, relying on the excellent transmission characteristics of topological valley states. However, existing structures still face issues such as limited design flexibility. In this paper, a high-performance topological all-optical logic device based on VPCs consisting of circular ring dielectric columns is designed and demonstrated. By introducing the inner radius as an independent design parameter, we construct a new type of VPC and systematically investigate its influence on the photonic band gap. Based on this, we design a beam splitter with high operational bandwidth and low insertion loss (<0.5 dB), and then realize fundamental OR and XOR logic gates, achieving extinction ratios of 18.9  dB for the OR gate and up to 44  dB for the XOR gate at an operating frequency of 193.5  THz. The platform also supports the NOT gate and, through cascading, can implement more logic functions such as AND gate.