Interferometric distributed optical-fiber sensor

Area of Science:

• Optical Engineering
• Sensor Technology
• Fiber Optics

Background:

• Distributed sensing offers real-time monitoring of physical parameters along optical fibers.
• Fiber-optic interferometers are sensitive to environmental changes, but precise localization of disturbances can be challenging.

Purpose of the Study:

• To develop and demonstrate a distributed fiber-optic sensor capable of both detecting and locating time-varying perturbations.
• To utilize a modified fiber-ring interferometer for enhanced spatial resolution of disturbances.

Main Methods:

• A novel interferometric technique employing a modified fiber-ring interferometer is presented.
• The system comprises a reflecting-fiber-ring interferometer and a differentiating-ring interferometer.
• Disturbance location is achieved by dividing the outputs of the two interferometers.

Main Results:

• The developed sensor provides a position-dependent response to perturbations such as strain and temperature.
• A signal proportional to the product of phase change rate and perturbation distance is obtained from the reflecting ring.
• The differentiating ring yields a signal proportional only to the phase change rate, enabling distance calculation.

Conclusions:

• The proposed technique successfully enables the detection and precise localization of perturbations along an optical fiber.
• The modified fiber-ring interferometer system offers a viable solution for distributed sensing applications.
• Experimental results with a 155-m sensor demonstrate the system's effectiveness.