Fully degeneracy-lifted bow-tie elliptical ring-core multi-mode fiber

Area of Science:

• Optical Fiber Communications
• Photonics
• Materials Science

Background:

• Traditional optical fibers suffer from mode degeneracy and coupling, limiting capacity in mode-division multiplexing (MDM).
• Existing fiber designs struggle to fully separate degenerate modes, necessitating complex digital signal processing (DSP).

Purpose of the Study:

• To introduce a novel bow-tie elliptical ring-core multi-mode fiber (BT-ERC-MMF) for enhanced mode separation.
• To investigate the fiber's performance, including its ability to support a large number of distinct eigenmodes.
• To assess the fiber's suitability for high-capacity optical communication systems.

Main Methods:

• Designing a fiber with a unique elliptical ring-core and bow-tie stress-applying parts (SAPs) to break symmetry.
• Utilizing conformal mapping to analyze the effect of bending on fiber performance.
• Simulating and analyzing broadband performance metrics across the C-band (1530-1565 nm).

Main Results:

• The BT-ERC-MMF supports 53 fully degeneracy-lifted eigenmodes at 1550 nm.
• A minimum effective index difference between adjacent modes exceeding 1.59 × 10⁻⁴ was achieved.
• Broadband performance, including effective modal index, index difference, effective mode area, nonlinearity, and chromatic dispersion, was comprehensively studied.

Conclusions:

• The designed BT-ERC-MMF effectively separates degenerate modes, enabling direct fiber eigenmode-division multiplexing.
• The fiber shows potential for high-capacity communication by combining mode-division multiplexing (MDM) with wavelength-division multiplexing (WDM).
• This advancement offers a path towards increased transmission capacity and spectral efficiency without complex MIMO-DSP.