Surface Enhanced Raman Scattering in purely Dielectric Structures via Bloch Surface Waves

We study surface-enhanced Raman scattering (SERS) in fully dielectric periodic structures supporting Bloch surface waves. We demonstrate a lower bound for the SERS enhancement of 50 when the optical pump is resonantly coupled to the Bloch surface wave supported by the structure. A corresponding photoluminescence experiment shows an emission enhancement of more than two orders of magnitude, suggesting that the actual SERS enhancement is 200. Analogous conclusions are obtained by means of a semiclassical theoretical model. These results suggest an alternative to plasmonic materials to enhance Raman scattering at a surface and are of interest to those working in the field of Raman as well as fluorescence spectroscopy.