Phase demodulation method in phase-sensitive OTDR without coherent detection.

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Sensing Technology
• Signal Processing in Optical Systems

Background:

• Traditional phase demodulation in φ-OTDR often requires complex configurations.
• Direct detection systems offer cost and simplicity advantages but lack robust phase demodulation.
• Existing methods may not be suitable for pure direct detection setups.

Purpose of the Study:

• To propose and demonstrate a novel phase demodulation method for direct detection φ-OTDR.
• To simplify the system configuration and reduce the cost of phase demodulation in φ-OTDR.
• To enable accurate phase demodulation using only intensity information from a direct detection system.

Main Methods:

• Deriving a pair of orthogonal signals from single-channel intensity data.
• Implementing phase demodulation using in-phase and quadrature (IQ) demodulation techniques.
• Applying various forms of piezoelectric transducer (PZT) induced vibrations to the optical fiber.

Main Results:

• Successful phase demodulation was achieved for different PZT-induced vibration patterns.
• The proposed method demonstrated effective phase demodulation capabilities.
• The experimental results confirmed the feasibility of the technique with a simplified system.

Conclusions:

• The developed method is the first to achieve phase demodulation in a pure direct detection φ-OTDR system.
• This approach significantly simplifies system configuration and lowers overall costs.
• The technique offers a practical and effective solution for phase demodulation in direct detection φ-OTDR applications.