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Intensity Demodulated Refractive Index Sensor Based on Front-Tapered Single-Mode-Multimode-Single-Mode Fiber
Jing Kang1, Jiuru Yang2,3, Xudong Zhang4
1College of Electronics Engineering, Heilongjiang University, Harbin 150080, China. 2171241@s.hlju.edu.cn.
Sensors (Basel, Switzerland)
|July 26, 2018
Summary
A new fiber optic sensor using a front-tapered single-mode-multimode-single-mode structure demonstrates high-resolution refractive index (RI) sensing. This intensity demodulated sensor offers superior performance compared to wavelength demodulation methods.
Area of Science:
- Optoelectronics
- Fiber optics
- Sensing technologies
Background:
- Refractive index (RI) sensing is crucial for various applications, including chemical analysis and environmental monitoring.
- Traditional RI sensors often face limitations in sensitivity, resolution, and cross-sensitivity.
- Fiber optic sensors offer advantages like remote sensing, immunity to electromagnetic interference, and small size.
Purpose of the Study:
- To theoretically and experimentally demonstrate a novel intensity demodulated refractive index (RI) sensor.
- To investigate the performance of a front-tapered single-mode-multimode-single-mode (FT-SMS) fiber structure for RI and temperature sensing.
- To compare the sensor's resolution and sensitivity with existing wavelength demodulation techniques.
Main Methods:
- Fabrication of the FT-SMS fiber structure using a flame-heated drawing technique.
- Analysis of the intensity feature in the taper area using the beam propagation method.
- Experimental testing for RI and temperature sensing, including cross-sensitivity analysis.
- Evaluation of sensor stability over a 2-hour continuous operation period.
Main Results:
- The FT-SMS sensor achieved a relative sensitivity of -342.815 dB/RIU for RI in the range of 1.33-1.37.
- The sensor's resolution reached 2.92 × 10-5 RIU, significantly outperforming wavelength demodulation.
- Temperature sensitivity was measured at 0.307 dB/°C with a cross-sensitivity error below 2 × 10-4.
- High stability was observed with wavelength fluctuations of ±0.045 nm and intensity fluctuations of ±0.386 dB.
Conclusions:
- The demonstrated FT-SMS fiber sensor effectively measures refractive index with high sensitivity and resolution.
- Intensity demodulation in the FT-SMS structure provides a superior alternative to wavelength demodulation for RI sensing.
- The sensor exhibits good stability and low cross-sensitivity to temperature, making it suitable for practical applications.
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