Optoplasmonic film for SERS.

Combining plasmonic and photonic elements, optoplasmonic hybrid structure exhibits excellent optical properties beyond conventional plasmonic or photonic structures. In this work, the optoplasmonic film consists of SiO2 microsphere and Au film without any nanostructures is investigated. With the help of a microsphere, the intensity of surface enhanced Raman spectroscopy (SERS) on Au film is highly enhanced (~1000 times) compared to bare Au film. The simulated electromagnetic field points out the enhancement caused by the optical lens effect of SiO2 microsphere that high light intensity is generated under the microsphere to excite surface plasmon on Au film. Furthermore, our data demonstrates the microsphere lens enhancement is greatly influenced by the size of the SiO2 microsphere and wavelength of incident light. This interesting film with a simple configuration could overcome the challenges in the fabrication and store process induced by nanostructures, which play an important role in SERS application. Our work not only enlarges the knowledge of the optoplasmonic hybrid structure, but also exhibits excellent application prospective in light harvest field e.g. enhanced spectrum, photocatalysis, optothermal effect, and hot electron generation, etc.