Fiber optic Surface Plasmon Resonance sensor based on wavelength modulation for hydrogen sensing.

Area of Science:

• Optoelectronics and Sensor Technology
• Materials Science for Gas Detection

Background:

• Fiber optic sensors offer remote and multiplexed sensing capabilities.
• Surface Plasmon Resonance (SPR) is a label-free optical sensing technique sensitive to refractive index changes.
• Hydrogen detection is crucial for safety and industrial process monitoring.

Purpose of the Study:

• To design and demonstrate a novel fiber optic SPR sensor for hydrogen detection.
• To utilize Palladium as a sensitive layer for enhanced hydrogen sensing performance.
• To investigate spectral modulation for a more reliable SPR sensor response.

Main Methods:

• Fabrication of a multilayer transducer (Silver/Silica/Palladium) on an optical fiber.
• Removal of optical cladding to enable SPR excitation.
• Utilizing Transverse Magnetic (TM) polarized light for sensing and Transverse Electric (TE) for reference.
• Analyzing spectral modulation of transmitted light for hydrogen presence.

Main Results:

• The sensor demonstrated sensitivity to hydrogen concentration via spectral shifts.
• An optimal configuration achieved a 17.6 nm resonant wavelength shift at 4% hydrogen in argon.
• The sensor relies on spectral modulation, offering improved reliability over intensity modulation.

Conclusions:

• The developed fiber optic SPR sensor with a Palladium layer shows promise for hydrogen detection.
• Multilayer thickness optimization is key to tuning sensor performance (wavelength shift and sensitivity).
• The use of TM and TE polarization provides a robust sensing mechanism.