Broadband intermodal fiber interferometer for sensor application: fundamentals and simulator.

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Interferometry

Background:

• Intermodal fiber interferometers are sensitive to external perturbations.
• Extracting utility signals from broadband sources presents challenges in signal stability and linearity.

Purpose of the Study:

• To analytically consider and experimentally implement an intermodal fiber interferometer.
• To demonstrate its capability for measuring external perturbations affecting multimode fiber optical length.
• To achieve a linear response and mitigate fading using specific signal processing techniques.

Main Methods:

• Analytical consideration of an intermodal fiber interferometer.
• Laboratory implementation of the optical scheme.
• Utilizing an optical spectrum analyzer and correlation functions for signal extraction.
• Introduction of contrast and fading coefficients for performance characterization.

Main Results:

• Demonstrated linear response to external perturbations.
• Achieved effective fading mitigation through signal processing.
• Derived analytical expressions for utility signal parameters.
• Established optimal operating conditions based on fiber length, light source spectrum width, and spectral resolution.

Conclusions:

• The developed intermodal fiber interferometer is applicable for sensing various physical quantities.
• The proposed scheme offers a robust and linear method for perturbation measurement.
• The introduced coefficients provide valuable metrics for interferometer performance evaluation.