Hybrid-enhancement synthesis of dual-interference signals and multiplexing structure optimization for push-pull...

Area of Science:

• Optical Engineering
• Sensor Technology
• Metrology

Background:

• Inline interferometric fiber Bragg grating (FBG) accelerometers face challenges with inter-channel response mismatch and noise floor limitations.
• Push-pull configurations double sensitivity but require signal synthesis due to independent interference channels, which are susceptible to asymmetry-induced errors.
• Structural asymmetry degrades synthesis fidelity, reducing sensitivity and increasing the noise floor in FBG accelerometers.

Purpose of the Study:

• To develop an asymmetry-compensated dual-interference-channel synthesis scheme for FBG accelerometers.
• To investigate and compare noise coupling mechanisms in wavelength-division multiplexing (WDM), time-division multiplexing (TDM), and space-division multiplexing (SDM) systems.
• To establish critical design criteria for high-performance sensor multiplexing structures.

Main Methods:

• A quantitative correlation model was established to analyze the impact of asymmetry on dual-channel amplitudes.
• An asymmetry-compensated synthesis scheme using a dynamic scaling factor was proposed to achieve precise channel matching.
• Noise coupling mechanisms were systematically investigated across WDM, TDM, and SDM multiplexing systems.

Main Results:

• A minute 1 mm asymmetry was found to induce a significant 7 rad response deviation in dual-channel amplitudes.
• Wavelength-division multiplexing (WDM) demonstrated superior performance, exhibiting 2.6 dB and 5.6 dB lower noise floor elevation compared to TDM and SDM, respectively.
• A WDM-based push-pull interferometric FBG accelerometer achieved a sensitivity of 53.18 dB (re: rad/g) and a minimum detectable acceleration of 6.43×10⁻⁸ g/Hz.

Conclusions:

• The proposed asymmetry-compensated scheme provides a universal solution for mismatches in FBG accelerometers, regardless of their origin.
• WDM is the optimal multiplexing method for minimizing noise floor elevation in dual-channel FBG accelerometer systems.
• The optimized WDM-based FBG accelerometer offers high sensitivity and low detectable acceleration with a simplified optical structure.