Plasmonic propagations distances for interferometric surface plasmon resonance biosensing.

Area of Science:

• Nanophotonics and Plasmonics
• Biosensing Technologies
• Thin Film Characterization

Background:

• Surface Plasmon Resonance (SPR) is a label-free optical technique widely used in biosensing.
• Current SPR schemes face limitations in traceability due to factors like coupled plasmon propagation distance.
• Enhancing SPR sensitivity and stability is crucial for advancing diagnostic and research applications.

Purpose of the Study:

• To propose and investigate a novel SPR scheme utilizing local phase modulations for enhanced traceability.
• To analyze the propagation distance of coupled plasmon modes in thin film microstructures.
• To examine the impact of surface roughness and dielectric properties on SPR performance.

Main Methods:

• Theoretical proposal of an SPR scheme based on phase-sensitive intensity modulations.
• Experimental investigation of coupled plasmon propagation in visible and near-infrared spectral regions.
• Characterization of substrate surface roughness using various dielectrics and deposition methods.
• Analysis of gold (Au) film properties, including surface roughness and dielectric constants, at different deposition rates.
• Study of an interferometric SPR setup with varying grating couplers to modulate plasmon propagation length.

Main Results:

• The proposed SPR scheme demonstrates increased traceability of SPR shifts for biosensing.
• Propagation distance of coupled plasmon modes is critically dependent on thin film microstructure and material properties.
• Surface roughness of dielectric substrates and gold films significantly influences plasmon propagation.
• Deposition methods and rates affect the quality and characteristics of thin gold films.
• Grating coupler design in interferometric SPR setups can be optimized to control plasmon propagation length.

Conclusions:

• The developed SPR scheme offers improved sensitivity and traceability for biosensing applications.
• Understanding and controlling coupled plasmon propagation distance is key to optimizing SPR sensor performance.
• Material selection, deposition techniques, and structural design are critical parameters for next-generation SPR biosensors.