Demodulation of the overlapping reflection spectrum of serial FBGs based on a weighted differential evolution...

Area of Science:

• Optoelectronics
• Fiber Optic Sensors
• Signal Processing

Background:

• Serial fiber Bragg gratings (FBGs) often exhibit overlapping reflection spectra due to similar wavelengths, complicating accurate wavelength demodulation.
• Existing methods struggle with precise analysis of these overlapping spectral features, limiting sensor network capabilities.

Purpose of the Study:

• To develop a novel demodulation model for overlapping reflection spectra of serial FBGs.
• To accurately calculate FBG wavelengths by encoding FBGs through reflectivity and utilizing spectrum similarity.
• To analyze factors influencing demodulation accuracy and validate the method experimentally.

Main Methods:

• A novel demodulation model based on spectrum similarity was developed.
• Fiber Bragg gratings (FBGs) were encoded using their reflectivity.
• A weighted differential evolution algorithm was employed for FBG wavelength calculation.
• Simulations and experiments were conducted to analyze accuracy and applicability.

Main Results:

• The proposed method successfully demodulated overlapping, partially overlapping, and non-overlapping reflection spectra of serial FBGs.
• Wavelength demodulation accuracy in fully overlapping situations for two, three, and four FBGs was achieved with errors of 4.5, 14.9, and 24.6 pm, respectively.
• The model's suitability was confirmed across different degrees of spectral overlap.

Conclusions:

• The novel demodulation model effectively addresses the challenge of overlapping spectra in serial FBGs.
• The weighted differential evolution algorithm provides accurate wavelength calculation for complex spectral conditions.
• This method enhances the performance and applicability of FBG-based sensing systems.