Long fiber Bragg grating sensor interrogation using discrete-time microwave photonic filtering techniques.

Area of Science:

• Photonics and Sensor Technology
• Optical Fiber Sensing
• Microwave Photonics

Background:

• Quasi-distributed sensing using long fiber Bragg gratings (FBGs) is crucial for event detection.
• Existing interrogation techniques may lack precision or robustness against environmental changes.

Purpose of the Study:

• To present and demonstrate a novel interrogation technique for photonic sensors based on long FBGs.
• To achieve precise detection and location of multiple spot events along the FBG sensor.

Main Methods:

• Utilized a technique for analyzing microwave photonics (MWP) filters to interrogate long FBGs.
• Employed a modulator and a photo-detector (PD) with a bandwidth under 1 GHz.
• Leveraged FBGs as quasi-distributed sensors for event detection.

Main Results:

• Demonstrated the capability to detect several hot-spots along the FBG.
• Achieved high spatial accuracy for event location, under 0.5 mm.
• The system showed intrinsic robustness against environmental variations.

Conclusions:

• The proposed interrogation system effectively detects and locates multiple events with high precision.
• The technique offers a robust and accurate solution for quasi-distributed fiber optic sensing.
• This method is suitable for applications requiring precise event localization in various environments.