Strong light/matter coupling for SERS

TL;DR

This paper demonstrates a novel multilayer cavity design that enhances light/matter coupling for surface-enhanced Raman scattering, enabling highly sensitive biomolecule detection with potential applications in health diagnostics.

Contribution

It introduces a new multilayer cavity architecture with silver multi-shape features and ITO layers, improving light/matter interaction for SERS-based biomolecular sensing.

Findings

Strong light/matter coupling confirmed by experimental and numerical results.

High sensitivity in detecting BSA protein via surface-enhanced Raman scattering.

Effective anticrossing energy measurement using a three-oscillator model.

Abstract

For a wide range of health applications, label-free sensing is essential, and micro-photonics offers innovative technical solutions to pursue important objectives. It has been shown that the strong light/matter coupling formed between a cavity and molecules through light excitation enhances biological and clinical applications by providing deep insights into molecular analysis. The multilayer cavity's proposed architecture is meant to promote a robust interaction between light and matter. The top layer was made of silver Ag multi-shape features that, after being synthesized and characterized, were immobilized on the surface, while a layer of indium tin oxide ITO was flipped to produce two distinct layouts. An investigation of the mode behavior was conducted to describe the two layouts; experimental and numerical results point to a strong light/matter interaction by the ITO/SiO2/spacer/Ag multi-shape feature design. For the characterization of the light/matter coupling, a fluorophore was deposited on the surface; the anticrossing energy was then examined by integrating the experimental data with a model of three mechanical oscillators. To show the system's sensitivity, the analysis was carried out again using bovine serum albumin (BSA) protein. The protein is water-soluble and exhibits an infrared absorption band (amide I), while also being active in the Raman region. Besides, it may consistently bind to Ag multi-shape features. The excellent sensitivity was demonstrated, enabling the use of image analysis to capture the surface-enhanced Raman scattering of the BSA. In conclusion, the suggested sensing approach brings up fresh possibilities for highly sensitive biomolecule detection techniques and encourages results when used as a fundamental sensing technique to investigate molecular patterns.