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Ultra-High-Sensitivity Humidity Fiber Sensor Based on Harmonic Vernier Effect in Cascaded FPI
Cheng Zhou1, Yanjun Song1, Qian Zhou1
1School of Electronic and Information Engineering, Harbin Institute of Technology, Shenzhen 518055, China.
Sensors (Basel, Switzerland)
|July 9, 2022
Summary
This study introduces an ultra-high-sensitivity fiber humidity sensor using a cascaded Fabry-Perot interferometer (FPI) and the harmonic Vernier effect (HVE). This novel sensor achieves significantly enhanced sensitivity for humidity detection.
Area of Science:
- Fiber optic sensing
- Interferometry
- Humidity detection
Background:
- Traditional Vernier effect (TVE) Fabry-Perot interferometers (FPIs) have limitations in optical path length matching.
- Achieving ultra-high sensitivity in FPI-based sensors is crucial for advanced applications.
Purpose of the Study:
- To propose and demonstrate an ultra-high-sensitivity fiber humidity sensor.
- To overcome the limitations of TVE FPIs using the harmonic Vernier effect (HVE).
Main Methods:
- Utilized a cascaded Fabry-Perot interferometer (FPI) with a chitosan film.
- Implemented the harmonic Vernier effect (HVE) for enhanced sensitivity.
- Employed an internal envelope tracking method for spectra demodulation.
Main Results:
- Achieved an ultra-high sensitivity of -83.77 nm/%RH.
- Demonstrated a magnification factor of -53.98 times.
- The HVE FPI sensor broke the strict optical path length matching condition of TVE FPIs.
Conclusions:
- The proposed HVE FPI sensor offers a pathway to ultra-high sensitivity in fiber optic sensing.
- The internal envelope tracking method enhances demodulation flexibility.
- This work provides a valuable guide for developing advanced fiber sensors.
