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Interrogation technique for TFBG-SPR refractometers based on differential orthogonal light states
Valérie Voisin1, Christophe Caucheteur, Patrice Mégret
1Electromagnetism and Telecommunication Department, Université de Mons, Mons, Belgium. valerie.voisin@umons.ac.be
Applied Optics
|August 12, 2011
Summary
This study introduces an automated method for measuring refractive index using gold-coated fiber Bragg gratings. The technique leverages surface plasmon resonance for precise, sensitive, and accurate refractive index sensing in solutions.
Area of Science:
- Optoelectronics
- Nanotechnology
- Chemical Sensing
Background:
- Surface plasmon resonance (SPR) in optical fiber sensors is sensitive to surrounding refractive index changes.
- Gold-coated tilted fiber Bragg gratings (TFBGs) exhibit SPR phenomena influenced by light polarization and material properties.
Purpose of the Study:
- To develop and demonstrate an automated demodulation technique for refractive index (RI) measurement.
- To utilize the polarization-dependent SPR in TFBGs for enhanced RI sensing.
Main Methods:
- Fabrication of gold-coated TFBGs.
- Recording transmission amplitude spectra for two orthogonal polarization states.
- Comparing differential amplitude of resonance peaks near plasmon attenuation for automated RI demodulation.
Main Results:
- Achieved a mean sensitivity exceeding 500 nm/RIU.
- Demonstrated accuracy of 5x10^-5 RIU.
- Validated the method over a 0.01 RIU range in aqueous solutions.
Conclusions:
- The proposed automated technique accurately measures surrounding refractive index.
- This method offers high sensitivity and precision for SPR-based fiber optic sensing.
- The polarization-dependent SPR in TFBGs provides a robust platform for RI sensing applications.
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