Comprehensive Modeling of Multimode Fiber Sensors for Refractive Index Measurement and Experimental Validation.

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Materials Science

Background:

• Refractive index (RI) sensing is crucial for various applications.
• Multimode fibers offer potential for novel sensor designs.
• Accurate modeling is needed to optimize RI sensor performance.

Purpose of the Study:

• To develop and validate a comprehensive model for RI sensing in multimode fibers.
• To investigate the RI response across three distinct sensing zones.
• To assess the sensor's performance over a wide RI range.

Main Methods:

• Combined ray optics, Gaussian beam, and wave optics analysis.
• Incorporation of interrogating lightwave characteristics into the model.
• Experimental validation using three fiber optic sensors with varying cladding lengths.

Main Results:

• The developed model accurately predicts RI response in all three sensing zones.
• Experimental results show high correlation with model simulations.
• Sensors demonstrate a wide dynamic RI range (1.316 to >1.608) at 1550 nm.
• A resolution of 2.2447 × 10^-5 RI unit (RIU) was achieved in Zone II.

Conclusions:

• The comprehensive model provides a reliable tool for designing and optimizing multimode fiber RI sensors.
• The validated sensors are suitable for applications requiring precise RI measurements over a broad range.
• The study highlights the potential of multimode fibers for high-resolution RI sensing.