Influence of a variable Rayleigh scattering-loss coefficient on the light backscattering in multimode optical fibers

Area of Science:

• Optics and Photonics
• Materials Science
• Wave Propagation

Background:

• Rayleigh backscattering is crucial for analyzing light propagation in optical fibers.
• Previous models often assumed a uniform scattering-loss coefficient.
• Understanding mode excitation is key to fiber optic performance.

Purpose of the Study:

• To develop an analytical diffraction technique for investigating Rayleigh backscattering in multimode optical fibers.
• To incorporate a variable Rayleigh scattering-loss coefficient within the fiber's cross-section.
• To analyze the impact of this variable coefficient on mode excitation levels.

Main Methods:

• Utilized a diffraction technique for analytical investigation.
• Supplemented the technique by accounting for a variable Rayleigh scattering-loss coefficient.
• Computed relative changes in radial and azimuthal mode excitation levels for quadratic- and step-index fibers.

Main Results:

• The excitation efficiency of different modes can either increase or decrease.
• The effect of a variable scattering-loss coefficient is more pronounced in quadratic-index fibers.
• The impact is negligible in typical multimode step-index fibers.

Conclusions:

• A variable Rayleigh scattering-loss coefficient significantly influences mode excitation in multimode optical fibers.
• Quadratic-index fibers exhibit a greater sensitivity to variations in the scattering-loss coefficient.
• The findings refine analytical models for optical fiber characterization.