Miniature interrogator for multiplexed FBG strain sensors based on a thermally tunable microring resonator array

Area of Science:

• Photonics and Sensing Technologies
• Optical Metrology
• Fiber Optic Sensors

Background:

• Fiber Bragg Gratings (FBGs) are widely used for sensing applications due to their robustness and multiplexing capabilities.
• Accurate interrogation of FBG sensors is crucial for high-resolution measurements.
• Existing interrogation methods face challenges in terms of resolution, size, and scalability.

Purpose of the Study:

• To develop a high-resolution and miniature multi-wavelength Fiber Bragg Grating (FBG) interrogator.
• To leverage a thermally tunable microring resonator (MRR) array for enhanced FBG sensing.
• To demonstrate the interrogator's capability for dynamic strain sensing with improved resolution and accuracy.

Main Methods:

• Utilized a thermally tunable microring resonator (MRR) array for FBG interrogation.
• Employed a phase detection method with dithering signals to generate an antisymmetric error signal.
• Implemented feedback locking between the MRR and FBG sensor for precise wavelength tracking.
• Experimentally demonstrated dynamic strain sensing for single and multiple FBGs.

Main Results:

• Achieved a dynamic strain resolution of 30 nε/√Hz over a frequency range of 100 Hz to 1 kHz.
• Demonstrated successful dynamic strain sensing for both single and multiple FBG sensors.
• The proposed interrogator exhibits significant improvements in resolution and wavelength accuracy compared to existing MRR-based interrogators.

Conclusions:

• The developed miniature FBG interrogator offers high-resolution dynamic strain sensing capabilities.
• The MRR-based approach provides superior performance in terms of resolution and accuracy.
• The system is promising for scalable and multiplexed sensing applications, particularly in demanding environments.