Dispersion relation of surface plasmons near photonic band gaps: influenceof the interaction with light

We present an experimental and theoretical study of the photonic band gap i n the propagation of surface plasmons (SPs) on periodically corrugated surf aces. Our main purpose is to investigate the case where the band gap width is larger than the energy distance between the SP dispersion curve for a fl at surface and the light line. We introduce a physical model of the interac tion of light waves with SPs and derive an analytical expression for the SP wave vector near band gaps based on the coupled-mode approach involving th ree interacting modes (two of them are SP modes and one is a light mode), B y using the interferometric measurement we have studied, for the first time , the SP propagation parameters in the vicinity of the photonic band gap (1 0 mum wavelength region). The predictions of our theory are in good agreeme nt with the experimental data.