Highly precise FBG wavelength demodulation method with strong multiplexing ability and positioning function based on...

Area of Science:

• Photonics
• Optical Sensing
• Signal Processing

Background:

• Microwave photonic filters (MPF) are crucial for signal processing.
• Fiber Bragg gratings (FBG) are widely used as sensing elements.
• Accurate wavelength demodulation is essential for FBG-based sensor systems.

Purpose of the Study:

• To propose a novel FBG wavelength demodulation method based on time-domain detection.
• To enhance the multiplexing capability of FBG sensors.
• To achieve high-precision positioning of FBGs.

Main Methods:

• Utilized microwave photonic filter (MPF) theory.
• Employed a vector network analyzer (VNA) to measure S21 parameters.
• Applied inverse discrete Fourier transform (IDFT) for time-domain conversion.
• Implemented normalization to mitigate spectrum overlap in multiplexed FBGs.

Main Results:

• Achieved a temperature sensitivity of 0.00503 °C.
• Demonstrated a positioning resolution of 1.25 cm.
• Determined the limit wavelength difference between two FBGs to be 0.25 nm.
• Validated high demodulation precision and multiplexing ability.

Conclusions:

• The proposed time-domain FBG demodulation method offers high precision and strong multiplexing ability.
• The technique enables high-precision positioning for FBG sensors.
• This method shows significant potential for various sensor applications.