[Spectra modulated surface plasmon resonance sensor based on side polished multi-mode optical fiber]

Area of Science:

• Optoelectronics
• Chemical Sensing
• Biomedical Engineering

Background:

• Surface plasmon resonance (SPR) is a label-less, high-sensitivity technique for chemical and biological analysis.
• Fiber optic sensors offer advantages in miniaturization and remote sensing capabilities.
• Improving spectral sensitivity in SPR sensors is crucial for enhanced detection limits.

Purpose of the Study:

• To enhance the spectral sensitivity of a side-polished fiber optic surface plasmon resonance sensor for refractive index (RI) measurements.
• To investigate the impact of structural modifications and material coatings on sensor performance.
• To evaluate the sensor's suitability for practical analytical applications.

Main Methods:

• Fabrication of a side-polished multimode fiber optic SPR sensor by removing cladding and part of the core.
• Coating the polished region with a chrome layer followed by a gold film.
• Characterization of the sensor's spectral sensitivity and refractive index detection range.
• Estimation of sensor resolution based on sensitivity and stability.

Main Results:

• The sensor demonstrated a wide refractive index measurement range from 1.333 to 1.431 RIU.
• Achieved an average spectral sensitivity of 4.11 x 10^3 nm/RIU, exceeding previously reported results.
• Exhibited a peak sensitivity of 1.09 x 10^4 nm/RIU in the higher refractive index range (1.417-1.431 RIU).
• Estimated a minimum resolution of approximately 3.6 x 10^-5 RIU.

Conclusions:

• The developed fiber optic SPR sensor offers superior spectral sensitivity and a broad detection range.
• The sensor's small size, stability, and reproducibility make it a promising candidate for real-world applications.
• Potential applications include food testing, environmental monitoring, and biomedical diagnostics.