Reduction of modal evolution fluctuation in 2-LP mode optical time domain reflectometry

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing

Background:

• Optical Time Domain Reflectometry (OTDR) is crucial for fiber optic diagnostics.
• Measurements in the 2-LP mode region present challenges due to mode coupling and polarization evolution.
• Rayleigh backscattering analysis is key to understanding signal behavior in optical fibers.

Purpose of the Study:

• To investigate OTDR performance in the 2-LP mode region.
• To analyze Rayleigh backscattering coefficients and polarization evolution.
• To propose and demonstrate a technique for reducing OTDR trace amplitude fluctuations.

Main Methods:

• Theoretical and experimental analysis of Rayleigh backscattering.
• Analysis of polarization state evolution of backscattered vector modes.
• Development and validation of a technique to mitigate LP11 mode intensity distribution effects.

Main Results:

• Characterization of Rayleigh backscattering amplitude coefficients from HE11 to higher-order modes.
• Clarification of polarization evolution in backscattered modes relative to the probe mode.
• Successful demonstration of a technique reducing OTDR trace fluctuations in lab and field settings.

Conclusions:

• The proposed technique effectively reduces amplitude fluctuations in OTDR traces.
• This method enhances the reliability of OTDR measurements in the 2-LP mode region.
• The findings are validated through practical demonstrations on optical fibers.