Abstract
Brillouin spectroscopy is a powerful tool for elasticity-sensitive non-invasive optical imaging. However, its relatively weak signal strength usually results long acquisition time and poor spectral quality. In this study, enhancements of Brillouin scattering at 532 nm was observed from various acoustic modes of alkaline-earth boroaluminosilicate glass coated with periodic arrays of gold nanodisks. The similar enhancements were also observed from the bulk phonons within the various liquids (including methanol and water) covered on the gold nanodisks. This enhancement is considered to be attributed by the surface plasmons generated by the nanostructures, and is found to be dependent on their geometries (i.e., aspect ratio and diameter) of the golden nanodisks. When employing the recent advances in virtually imaged phased array (VIPA) based background-free Brillouin spectrometers, the acquisition time could even be further optimized. The results of this study suggest that nanodisk arrays can provide a platform for practical implementation of surface-enhanced Brillouin scattering analogous to other surface-enhanced spectroscopies, and suggest an approach for further reduce the integration time for Brillouin spectroscopy.