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Cladding Mode Fitting-Assisted Automatic Refractive Index Demodulation Optical Fiber Sensor Probe Based on Tilted
Wenwei Lin1,2, Weiying Huang3, Yingying Liu1,2
1Research Center for Advanced Optics and Photoelectronics, Department of Physics, College of Science, Shantou University, Shantou 515063, China.
Sensors (Basel, Switzerland)
|April 23, 2022
Summary
This study introduces a new algorithm for faster refractive index sensing using tilted fiber Bragg gratings (TFBG) and surface plasmon resonance (SPR). The method improves calibration and measurement speeds for surrounding refractive index (SRI) detection.
Area of Science:
- Photonics and Optical Sensing
- Fiber Optic Sensors
- Biomedical Instrumentation
Background:
- Surface Plasmon Resonance (SPR) is a powerful optical sensing technique.
- Tilted Fiber Bragg Gratings (TFBG) offer enhanced sensitivity for refractive index measurements.
- Accurate and rapid detection of surrounding refractive index (SRI) is crucial in various scientific applications.
Purpose of the Study:
- To develop a novel algorithm for accelerating the calibration and measurement of SRI using SPR in a TFBG.
- To demonstrate automatic selection of the most sensitive cladding mode for enhanced sensor performance.
- To investigate the trade-offs between scanning speed and sensitivity in SRI detection.
Main Methods:
- Utilizing SPR in a TFBG for cladding mode interrogation.
- Preparing refractive index samples with a small index step (2.2 × 10-5) using glucose solutions.
- Implementing an algorithm for automatic selection of sensitive cladding modes by comparing their sensitivities.
- Analyzing the impact of reduced wavelength resolution on scanning speed and SRI sensitivity.
- Applying parabolic equation calculation and weighted Gauss fitting to improve sensitivity.
Main Results:
- Achieved a highest sensitivity of -6887 dB/RIU with a scanning time of 15.77 s.
- Reduced scanning time to as low as 1.58 s by decreasing wavelength resolution.
- Observed a decrease in SRI sensitivity with reduced resolution, ranging from 17.5% to 36.7%.
- Improved sensitivity to -6332 dB/RIU and -6721 dB/RIU for 0.07 nm resolution, and -5850 dB/RIU and -6228 dB/RIU for 0.14 nm resolution through data fitting techniques.
Conclusions:
- The proposed novel algorithm effectively accelerates SRI demodulation and calibration in SPR-TFBG sensors.
- Automatic selection of sensitive cladding modes and data processing techniques enhance sensor efficiency and accuracy.
- The study provides a viable method for rapid and sensitive refractive index measurements, balancing speed and sensitivity.
