High-sensitivity optical fiber relative humidity probe with temperature calibration ability.

Area of Science:

• Photonics and Optical Sensing
• Materials Science
• Environmental Monitoring

Background:

• Accurate measurement of relative humidity (RH) and temperature is crucial for various applications.
• Existing RH sensors often suffer from cross-sensitivity to temperature, complicating measurements.
• Optical fiber sensors offer advantages like remote sensing, immunity to electromagnetic interference, and miniaturization.

Purpose of the Study:

• To propose and demonstrate a high-sensitivity optical fiber relative humidity (RH) sensing probe.
• To incorporate temperature calibration capabilities for accurate RH measurements.
• To achieve simultaneous measurement of both temperature and RH using a single probe.

Main Methods:

• Fabrication of a Fabry-Perot interferometer (FPI) by coating a single-mode fiber end face with a thin polyimide (PI) film.
• Integration of an upstream fiber Bragg grating (FBG) for temperature compensation.
• Experimental characterization of the probe's response to varying RH and temperature levels.

Main Results:

• The proposed sensing probe successfully achieved simultaneous measurement of temperature and RH.
• The RH response sensitivity reached a high value of 986.25 pm/%RH.
• The cascaded FBG effectively eliminated temperature cross-sensitivity, ensuring accurate RH readings.

Conclusions:

• The developed optical fiber sensor provides a robust solution for simultaneous temperature and RH monitoring.
• The probe's simple structure, high sensitivity, and dual-parameter measurement capability offer extensive application prospects.
• This technology is well-suited for applications requiring precise environmental sensing.