Simple method for analyzing the birefringence of an elliptical-core fiber by an equivalent rectangular waveguide.

Area of Science:

• Optics and Photonics
• Materials Science
• Waveguide Theory

Background:

• Birefringence in optical fibers is crucial for polarization-maintaining applications.
• Analyzing elliptical-core fibers presents unique challenges due to their geometry.
• Existing analytical methods may be computationally intensive or less accurate for complex structures.

Purpose of the Study:

• To introduce a simplified analytical method for calculating birefringence in elliptical-core fibers.
• To validate the accuracy of the proposed method against established numerical and approximate techniques.
• To demonstrate the method's potential for analyzing waveguides with arbitrary cross-sectional geometries.

Main Methods:

• Utilized first-order perturbation theory applied to an equivalent rectangular-core waveguide model.
• Developed a simplified analytical approach to approximate the birefringence characteristics.
• Compared the derived results with those obtained from finite-element analysis and another approximate technique.

Main Results:

• The proposed simple method accurately predicts the birefringence of elliptical-core fibers.
• Results show strong agreement between the perturbation theory approach and finite-element analysis.
• The method's simplicity and accuracy are demonstrated through comparative analysis.

Conclusions:

• The developed method provides an efficient and accurate means to analyze elliptical-core fiber birefringence.
• This technique offers a valuable alternative to more complex computational methods.
• The methodology is extensible to a broader range of waveguide geometries.