Signal processing method based on group delay calculation for distributed Bragg wavelength shift in optical frequency...

Area of Science:

• Optoelectronics
• Signal Processing
• Fiber Optics

Background:

• Distributed measurements of long fiber Bragg gratings (FBGs) are crucial for structural health monitoring.
• Optical frequency domain reflectometry (OFDR) is a key technique for such measurements.
• Conventional signal processing methods can be computationally intensive and time-consuming.

Purpose of the Study:

• To introduce a novel, computationally efficient signal processing method for distributed FBG measurements using OFDR.
• To enhance the sensitivity of detecting non-uniform strain distributions in long FBGs.
• To reduce the signal processing time compared to traditional methods.

Main Methods:

• A signal processing method based on group delay calculations was developed for OFDR signals.
• Bragg wavelength shifts were interpreted as group delay to determine wavelength shift distribution.
• A weighted averaging process was incorporated for effective noise reduction.

Main Results:

• The proposed method achieved high computational efficiency, requiring only 3.5% of the processing time of conventional methods.
• The technique demonstrated high sensitivity to experimental signals, particularly for non-uniform strain distributions.
• Accurate distribution of Bragg wavelength shifts was obtained.

Conclusions:

• The group delay-based signal processing method offers a significant improvement in efficiency and sensitivity for distributed FBG measurements.
• This method is well-suited for analyzing strain distributions in long FBGs using OFDR.
• The technique provides a valuable tool for advanced optical sensing applications.