Cascaded microfiber interferometer-fiber Bragg grating sensor for decoupled strain and temperature measurement.

Area of Science:

• Optoelectronics and Photonics
• Fiber Optic Sensors
• Materials Science

Background:

• Accurate strain and temperature monitoring is crucial in various engineering applications.
• Traditional sensors often suffer from cross-sensitivity, complicating data interpretation.
• Optical fiber sensors offer advantages like remote sensing and immunity to electromagnetic interference.

Purpose of the Study:

• To develop and investigate an optical fiber sensing scheme for decoupled strain and temperature measurement.
• To utilize a cascaded microfiber interferometer-fiber Bragg grating (MFI-FBG) configuration for enhanced sensing capabilities.
• To establish a method for suppressing strain-temperature cross-sensitivity.

Main Methods:

• A cascaded MFI-FBG configuration was employed, with MFI acting as the strain sensor and FBG as the temperature reference.
• Experimental characterization of wavelength response to applied strain for the MFI.
• Temperature characterization of both MFI and FBG sensing units.
• Development of a sensitivity matrix to decouple strain and temperature signals.

Main Results:

• The MFI demonstrated a linear wavelength response to strain (sensitivity: 0.0226 nm/µɛ, R²: 0.9875).
• Both MFI and FBG showed stable and repeatable responses to temperature changes (MFI: 0.0112 nm/°C, FBG: 0.0075 nm/°C).
• The established sensitivity matrix effectively suppressed cross-sensitivity, enabling independent demodulation.

Conclusions:

• The proposed MFI-FBG configuration enables accurate and decoupled measurement of strain and temperature.
• The distinct spectral responses of MFI and FBG are effectively utilized for cross-sensitivity suppression.
• This sensing scheme holds significant potential for structural health monitoring and other applications requiring precise environmental sensing.