Molecules close to metal nanostuctures which are illuminated by light exhibit a complex electic field. They experience electric forces along the field lines, which become very crowded in sharp regions of the nanostructures, such as corners or tips, and in the regions of high electron density. These regions of crowded field lines are called hotspots which are generally localized to small spots. If it would be possible to expand the local field enhancements to the whole sample surface, heating which limits the field enhancement could be avoided and the interaction with molecules would be increased.
Ventsislav Valev (Katholieke Universiteit Leuven) and co-workers could now demonstrate that such near-field enhancements can be extended over an entire nanopatterned gold surface. The extension of the near-field is achieved by driving the electron density along ring-shaped nanostructures with circularly polarized light. They validated their concept by two sets of numerical simulations as well as by a clear experimental confirmation. The homogeneous field enhancement increases the interaction cross-section with molecules which will be useful for chemical and sensing applications.
The research was reported in Advanced Optical Materials, a new section in Advanced Materials dedicated to breakthrough discoveries and fundamental research in photonics, plasmonics, metamaterials, and more, covering all aspects of light-matter interactions. To get Advanced Optical Materials email alerts click here.