Optical Bistability with Surface Plasmons Beyond Plane Waves in Nonlinear Dielectric

Abstract

Wysin et al [1] suggested that the local field enhancement near a metal surface which occurs if surface plasmons are excited in a metal film, can be useful for observing optical bistability arising from the nonlinearity of the Kerr medium. Other geometrical arrangements [2] have also been suggested. These studies assume plane waves (with intensity-dependent propagation vectors) in the nonlinear medium and use the Fresnel formulae for reflection and refraction from a layered medium but with linear refractive index replaced by the nonlinear refractive index. This assumes that the fields in the medium are homogeneous. However, if surface plasmons are excited, then the fields are inhomogeneous and one has the problem of reflection and refraction from an inhomogeneous layered medium. The inhomogeneity is to be determined self-consistently. Thus a proper treatment of optical bistability with surface plasmons should use the nonlinear solutions of the wave equation in Kerr medium. This is what we do in this paper. We also present results for optical bistability with long-range surface plasmons, which typically lead to much lower switching intensities.