Plasmonic optical fiber sensors: enhanced sensitivity in water-based environments

Area of Science:

• Photonics and Optical Sensing
• Nanotechnology
• Biomedical Engineering

Background:

• Refractometric sensors are crucial for measuring liquid properties.
• Existing sensors face limitations in sensitivity and dynamic range.
• Integrating long period gratings (LPG) with localized surface plasmon resonance (LSPR) offers potential for enhanced performance.

Purpose of the Study:

• To develop and characterize a highly sensitive refractometric fiber sensor.
• To investigate the synergistic effect of LPG and LSPR for improved refractive index sensing.
• To establish the sensor's performance metrics within a specific refractive index range.

Main Methods:

• Fabrication of a 3.15-mm long period grating (LPG) transducer.
• Coating the LPG with 2-7 nm gold nanoparticles to induce localized surface plasmon resonance (LSPR).
• Operating the sensor by monitoring energy transference from LPG cladding modes to LSPR at a 568 nm wavelength.

Main Results:

• The sensor demonstrated high sensitivity of 208%/unit of refractive index at a refractive index of 1.39.
• Achieved a resolution better than 0.0003 within the refractive index range of 1.3629 to 1.4479.
• The sensor's operation relies on the coupling between LPG cladding modes and LSPR.

Conclusions:

• The developed LPG-LSPR fiber sensor offers significantly improved sensitivity and resolution for refractometric applications.
• This hybrid approach provides a promising platform for advanced optical sensing.
• The sensor is suitable for applications requiring precise measurement of refractive indices in the tested range.