Plasmonics manuscript No. (will be inserted by the editor) Large Optical Nonlinearity of Surface Plasmon Modes on Thin Gold

Abstract We investigate the optical nonlinear effects of a long-range surface-plasmon polariton mode prop-agating on a thin gold film. These effects may play a key role in the design of future nanophotonic circuits as they allow for the realization of active plasmonic el-ements. We demonstrate a significant enhancement of the transmission on a timescale below a millisecond as well as a phase shift exceeding 2π already for modes