Mid-infrared surface plasmon resonance fiber optic sensors

Area of Science:

• Photonics and Sensing
• Optical Fiber Technology
• Plasmonics

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for detecting changes in refractive index.
• Traditional SPR sensors often use visible light, limiting probing depth.
• The mid-infrared (MIR) spectrum offers unique advantages for sensing applications.

Purpose of the Study:

• To propose and demonstrate the first mid-infrared (MIR) surface plasmon resonance (SPR) fiber optic sensor.
• To investigate the performance of a D-shaped multimode silica optical fiber coated with indium tin oxide (ITO) for MIR-SPR sensing.
• To explore the potential of MIR-SPR for enhanced sensitivity and gas detection.

Main Methods:

• Fabrication of a D-shaped multimode silica optical fiber sensor.
• Coating the fiber with a 105 nm indium tin oxide (ITO) layer.
• Experimental characterization of the sensor's SPR response in the mid-infrared region.

Main Results:

• The sensor exhibited resonance around 2700 nm.
• Achieved a high refractive index sensitivity of 1065.70 nm/RIU for refractive indices from 1.33 to 1.42.
• Demonstrated the feasibility of using MIR wavelengths for increased probing depth and potential for gas detection.

Conclusions:

• The developed MIR-SPR fiber optic sensor is a significant advancement in sensing technology.
• The use of MIR wavelengths enhances probing depth, improving potential sensitivity and signal-to-noise ratio.
• This technology holds promise for sensitive gas detection due to the alignment with the molecular fingerprint region.