Simultaneous Temperature and Strain Measurements Using Polarization-Maintaining Few-Mode Bragg Gratings

Area of Science:

• Optoelectronics
• Fiber Optic Sensors
• Materials Science

Background:

• Accurate simultaneous measurement of temperature and strain is crucial for structural health monitoring and industrial process control.
• Existing fiber optic sensors face challenges in achieving high sensitivity and discrimination for multiple parameters.

Purpose of the Study:

• To demonstrate simultaneous measurement of temperature and strain using a polarization-maintaining few-mode Bragg grating (PM-FMF-FBG).
• To analyze the wavelength and phase modulation characteristics of the even LP11 mode for sensing applications.

Main Methods:

• Utilized a polarization-maintaining few-mode Bragg grating (PM-FMF-FBG).
• Employed wavelength and phase modulation of the even LP11 mode for interrogation.
• Leveraged polarization interference for selective polarization excitation of reflection spectra.

Main Results:

• Achieved simultaneous temperature and strain measurement with a discrimination efficiency of 98%.
• Measured wavelength shift sensitivities of 10 pm·°C⁻¹ (temperature) and 0.73 pm·με⁻¹ (strain).
• Measured phase sensitivities of -3.2 × 10⁻² rad·°C⁻¹ (temperature) and 4 × 10⁻⁴ rad·με⁻¹ (strain).

Conclusions:

• The developed PM-FMF-FBG sensor effectively enables simultaneous and accurate measurement of temperature and strain.
• Experimental results for phase sensitivity show good agreement with theoretical calculations.
• This technology holds promise for advanced sensing applications requiring multi-parameter detection.