Design of Multi-Core Hollow-Core Photonic Bandgap Fibers

Hollow-core photonic bandgap fibers (HC-PBFs) demonstrate exceptional performance with high damage threshold, low nonlinearity, low thermal sensitivity and ultralow bending loss. However, the spatial efficiency of HC-PBFs is constrained by the absence of the multi-core structure. In this study, we present a detailed proposal and design of multi-core HC-PBFs for the first time. The structure model of multi-core HC-PBFs are constructed and the structure parameters are optimized by the loss, mode, coupling, bending characteristics based on offset-core, scaling-core, and dual-core three structure models. Finally, three kinds of multi-core HC-PBFs structures including homogeneous weakly-coupled, heterogeneous weakly-coupled, and strongly-coupled are designed with comprehensive structure and performance parameters. Simulation results indicate low loss, quasi single-mode, low crosstalk, negligible bending loss, and remarkable multi-core guiding performance. The introduction of a multi-core structure expands the potential applications of HC-PBFs in fiber communications and long-haul miniaturized fiber optic gyroscopes, high power delivery, fiber sensing, etc.