Tailoring cavity coupled plasmonic substrates for SERS applications

Area of Science:

• Plasmonics
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity and specificity for biosensing.
• Optimizing light coupling into plasmonic nanostructures is key to enhancing SERS substrate performance.
• Engineered substrates are needed to improve light-matter interactions for advanced SERS applications.

Purpose of the Study:

• To demonstrate a cavity-coupled structure for enhanced light-matter interaction and improved SERS performance.
• To investigate the influence of cavity length and wavelength on SERS signal modulation.
• To fabricate and characterize cost-effective, large-area cavity-coupled plasmonic substrates.

Main Methods:

• Numerical simulations were employed to model the optical properties of cavity-coupled structures.
• Fabrication of substrates involved depositing gold nanospheres onto indium tin oxide (ITO)-Au-glass layers.
• Experimental characterization of SERS enhancement was performed using the fabricated substrates.

Main Results:

• Cavity-coupled structures demonstrated the ability to enhance or suppress SERS signals based on design parameters.
• Simulations predicted tunable SERS signal modulation with cavity length and wavelength.
• Fabricated substrates showed a nearly 9-fold improvement in SERS enhancement compared to uncoupled designs.

Conclusions:

• The cavity-coupling approach effectively enhances light-matter interactions for superior SERS performance.
• Low-cost, large-area fabrication methods are viable for producing these advanced plasmonic substrates.
• This technique holds potential for improving other plasmonic phenomena, including trapping, catalysis, and nonlinear signal generation.