Enhanced Sensitivity in D-Shaped Optical Fiber SPR Sensor via Ag-α-Fe₂O₃ Grating

Area of Science:

• Optoelectronics
• Nanotechnology
• Biomedical Engineering

Background:

• Surface Plasmon Resonance (SPR) sensors offer high sensitivity for real-time analysis.
• Optical fiber SPR sensors are crucial for biomedical and environmental monitoring.
• Composite materials enhance SPR sensor performance.

Purpose of the Study:

• To numerically investigate and optimize a D-shaped fiber SPR sensor.
• To explore the use of a silver-hematite (Ag-α-Fe2O3) composite grating.
• To determine optimal geometric parameters for enhanced sensing characteristics.

Main Methods:

• Finite element simulations were employed for systematic numerical investigation.
• Parameter analysis focused on layer thicknesses, grating gap width, and cladding thickness.
• Optimization of the Ag-α-Fe2O3 composite grating structure was performed.

Main Results:

• Optimal silver layer thickness: 45 nm; α-Fe2O3 thickness: 12 nm for electric field confinement.
• Grating gap width of 30 nm maximized sensitivity via localized surface plasmon resonance.
• Residual cladding thickness of 0.5 μm balanced detection accuracy and sensitivity.

Conclusions:

• Fundamental design principles for high-performance SPR sensors were established.
• Critical relationships between geometric parameters and sensing characteristics were elucidated.
• Insights provided for developing next-generation sensors for advanced environmental and medical applications.