Abstract

The use of surface plasmons (SP) is recognized as being central to the development of nanoscale assemblies of photonic and opto-electronic devices.^1-4This is motivated by the spatially confined nature of these electromagnetic waves as well as their resonant behavior.⁵Amongst plasmonic supporting structures, Surface Plasmonic Crystals (SPCs) draw particular interest because of their tailored optical properties.⁶A geometry common to SPCs consists in a periodic arrangement of holes or slits in a metal film. Their complex optical response is then governed by coherent interactions between Bloch modes at the film’s interfaces and modes supported by the holes or slits. These modes have recently shown the potential to trigger low-power non-linear optical processes enabling active nanostructured materials to be developed.⁷One promising possibility to tailor non-linear optical functionalities such as modulation/transistor and stimulated/enhanced luminescence emission properties consists in creating hybrid structures which result from the electromagnetic coupling between a SPC and an active material demonstrating a strong non-linear response.⁸We studied the non-linear optical response of a Surface Plasmon Polaritonic Crystal hybridized with a non-linear polymer. The experiments were performed in a two-color pump-probe configuration for the pump wavelengths of 488 nm and 514 nm. Monitoring the crystal’s transmission as a function of the pump beam intensity and wavelength allowed for the observation of different non-linear responses at selected probe wavelengths. For a pump wavelength of 514 nm the crystal’s transmission showed a strong non-linear variation only. At 488 nm the transmission also demonstrated a bistable behavior. We explain the effect by considering the different density of states populated at the pump wavelengths used. At 488 nm both a strong non-linearity and a feedback mechanism are triggered allowing for a bistable behavior of the plasmonic crystal. These experimental observations are discussed on the basis of the results obtained from numerical calculations accounting for the Kerr response of the non-linear polymer.

© 2007 IEEE