On-chip phase interrogator based on a silicon Michelson interferometer for wavelength-multiplexed FBG sensors

Area of Science:

• Photonics
• Optical Sensing
• Integrated Optics

Background:

• Fiber Bragg Grating (FBG) accelerometers are crucial for measuring acceleration.
• Demodulating FBG sensors typically requires complex interrogation systems.
• Silicon-on-insulator (SOI) platforms offer potential for integrated optical devices.

Purpose of the Study:

• To demonstrate the feasibility of demodulating FBG accelerometers using an on-chip Michelson interferometer (MI).
• To integrate MI with waveguide Bragg gratings (WBGs) on an SOI platform.
• To achieve dynamic demodulation of fiber optic accelerometers (FOAs) using phase generated carrier (PGC) techniques.

Main Methods:

• Fabrication of an on-chip MI by integrating a multimode interferometer (MMI) with WBGs on an SOI platform.
• Utilizing thermal tuning of the on-chip MI for wavelength division multiplexing.
• Employing phase generated carrier (PGC) demodulation techniques for dynamic signal processing.

Main Results:

• The on-chip MI exhibited an output spectral bandwidth of 14 nm and a free spectral range (FSR) of 0.84 nm.
• Successful dynamic demodulation of FBG accelerometers was achieved.
• The system demonstrated a dynamic acceleration resolution of 0.204 mg/Hz, validated against a commercial FBG interrogator.

Conclusions:

• The integrated SOI-based MI platform is feasible for demodulating FBG accelerometers.
• The PGC demodulation technique enables effective dynamic sensing.
• This approach offers a compact and potentially cost-effective solution for FBG accelerometer interrogation.