Miniature and low-power high-precision FBG interrogator with self-temperature compensation.

Area of Science:

• Photonics and Optical Engineering
• Sensor Technology
• Instrumentation

Background:

• Fiber Bragg Grating (FBG) sensors are widely used for various measurement applications.
• Existing FBG interrogators can be bulky and sensitive to temperature fluctuations.
• There is a need for compact, accurate, and temperature-stable FBG interrogation systems.

Purpose of the Study:

• To design and fabricate a compact FBG interrogator with high accuracy and stability.
• To develop a novel demodulation technique for precise wavelength measurement.
• To implement temperature compensation without conventional cooling.

Main Methods:

• Integration of an arrayed waveguide grating (AWG) chip, photodiode (PD) array, and demodulation circuits into a small form factor (85×60×40 mm³).
• Development and application of a novel three-point demodulation technique for center wavelength determination.
• Utilizing a look-up table (LUT) with interpolation for temperature compensation, replacing thermoelectric coolers (TECs).

Main Results:

• Achieved wavelength demodulation stability of 0.55 pm and resolution of 1.65 pm.
• Demonstrated absolute wavelength demodulation accuracy of 2.7 pm under ideal conditions.
• Enhanced absolute wavelength demodulation accuracy to within 21.5 pm over a 10 °C to 60 °C range, a ~19-fold improvement.

Conclusions:

• The developed compact FBG interrogator offers high accuracy, stability, and temperature adaptability.
• The novel demodulation and temperature compensation techniques significantly improve performance.
• The interrogator's small size and low power consumption make it suitable for diverse FBG sensing applications.