Multicore fiber-Bragg-grating-based directional curvature sensor interrogated by a broadband source with a sinusoidal...

Area of Science:

• Optical Engineering
• Fiber Optic Sensors
• Instrumentation and Measurement

Background:

• Fiber Bragg gratings (FBGs) are widely used in sensing applications.
• Conventional interrogation methods for FBGs can be sensitive to spectral drift.
• Accurate and robust curvature sensing is crucial in various engineering fields.

Purpose of the Study:

• To propose a simple, spectral-drift-insensitive interrogation scheme for multicore fiber Bragg grating (FBG)-based directional curvature sensors.
• To develop a method that transforms wavelength shifts into measurable power variations.
• To enable precise interrogation of FBG peak wavelengths using a single photodiode.

Main Methods:

• Utilizing a broadband source with a sinusoidal spectrum to convert FBG wavelength shifts into reflected power variations.
• Deriving a closed-form expression for the relationship between FBG reflected power and peak wavelength.
• Implementing the scheme with a multicore FBG-based curvature sensor.

Main Results:

• The proposed interrogation scheme achieves a demodulated wavelength error within ±20 pm, outperforming conventional optical spectrum analyzer methods.
• The system successfully interrogates direction and curvature using a multicore FBG.
• The interrogated curvature measurement exhibits an error of less than 8%.

Conclusions:

• The developed spectral-drift-insensitive scheme offers a simple and precise method for interrogating FBG sensors.
• This technique enhances the accuracy and robustness of directional curvature sensing.
• The findings pave the way for more reliable fiber optic sensing systems.