Mode Couplers and Converters Based on Dual-Core Hollow-Core Photonic Bandgap Fiber

Abstract

We propose mode couplers and converters based on dual-core hollow-core photonic bandgap fiber (HC-PBGF) structures, which might be potential solutions for integrated all-fiber multiplexers or demultiplexers of a mode-division multiplexed (MDM) transmission system using HC-PBGFs. Coupling properties of LP01 and LP11 mode in the mode coupler are investigated and applied to mode separators and polarization separators. Mode transition from LP01 to LP11 and LP21 mode are demonstrated in the mode converter whose smaller core is expected as input end and matched with single-mode fiber. The coupling between fundamental mode and high-order modes is accomplished through the resonant effect, which is fulfilled by modifying the structure parameter of the smaller core. Such mode converters based on dual-core HC-PBGF could be a promising substitute for the free-space coupling device, which is costly and not suitable for integration design in MDM systems and other hollow-core fiber experiments and applications.

Keywords

• Fiber communication
• fiber couplers
• hollow-core photonic bandgap fiber
• mode conversion.