Optimization method for low-loss single-mode bending negative curvature anti-resonant hollow-core fiber designed by...

Area of Science:

• Optical Fiber Technology
• Photonics
• Materials Science

Background:

• Negative curvature hollow-core fibers (NC-HCFs) offer low loss transmission but often lack bending resistance.
• Controlling mode properties (fundamental mode - FM, higher-order mode - HOM) is crucial for advanced optical applications.
• Existing NC-HCF designs struggle to balance low loss with robust performance under bending.

Purpose of the Study:

• To propose and verify a novel design methodology for NC-AR-HCFs with improved bending resistance.
• To enable adjustable control over FM and HOM characteristics within these fibers.
• To provide a physical understanding of mode coupling for targeted fiber optimization.

Main Methods:

• Development of a design method for NC-AR-HCFs focusing on bending resistance.
• Proposal and simulation/fabrication of an asymmetric double-ring NC-HCF (ADR-NC-HCF) to validate the design approach.
• Analysis of mode coupling phenomena within the ADR-NC-HCF structure.

Main Results:

• The proposed ADR-NC-HCF demonstrates a low FM loss of 0.8 dB/km at 1550 nm, even with a small bending radius of 20 mm.
• Detailed analysis revealed the underlying physical principles governing mode coupling in the designed fiber.
• The design principle allows for directional optimization towards lower FM loss or higher HOM extinction ratios.

Conclusions:

• The presented design method effectively enhances the bending resistance of NC-AR-HCFs.
• The ADR-NC-HCF serves as a practical demonstration of the method's efficacy.
• This work provides a pathway for engineering hollow-core fibers with tailored mode properties for specific applications.