Differential group delay estimation of bent two-core fibers using an approximate solution

Area of Science:

• Optical Fiber Communications
• Photonics
• Wave Propagation

Background:

• Coupled multi-core fibers (MCFs) exhibit reduced differential group delay (DGD) due to random inter-core coupling.
• Understanding DGD is crucial for high-speed optical data transmission in MCFs.

Purpose of the Study:

• To develop a novel analytic approach for interpreting DGD reduction in bent and twisted MCFs.
• To model the influence of manufacturing errors and non-uniform bending on DGD and pulse broadening.

Main Methods:

• Approximate solution of two-core coupled mode equations for bent and twisted fibers.
• Derivation of distribution functions for group delay times of propagating pulse waves.
• Numerical calculation of DGD and pulse width using weighted averages based on derived distribution functions.

Main Results:

• Two distinct DGD and pulse width evolution regimes identified based on the rate of distribution function evolution.
• Small DGD and square-root distance dependence for pulse width observed when distribution functions rapidly reach their final state.
• Linear DGD increase and convex pulse width growth observed when distribution functions do not fully evolve.

Conclusions:

• The proposed analytic method accurately predicts DGD and pulse broadening in MCFs, aligning with simulation results.
• The study provides a framework for understanding and managing DGD in practical MCF applications.
• The findings highlight the importance of fiber parameters and manufacturing consistency in controlling optical signal integrity.