We propose the use of Fabry-Perot cavities as a means to augment the enhancement factor in surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) experiments by optical interference. Using both clean-room and bench-top fabrication approaches, we demonstrate that such a design can be readily realized and provides an additional 12× SERS enhancement and 5× TERS enhancement, in good agreement with expectations from electromagnetic modeling. The mechanism of optical interference enhancement is of far-field nature and is independent of the enhancement mechanisms relying on plasmonic and molecular resonances. Therefore, the Fabry-Perot cavity substrate can be applied generally without material and molecular limitations. The Fabry-Perot cavity structure provides enhancement at large incidence angles away from the surface normal, particularly suitable for low-light Raman measurements with side illumination.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films