All-Optical Waveguide-Type Switch Using Saturable Absorption in Graphene

Abstract

An all-optical switch using saturable absorption that accompanies refractive-index change such as in graphene films is proposed. The switching conditions are theoretically derived for arbitrary values of absorption and refractive-index change. It is found that switching can be performed by weaker control light when the refractiveindex change is accompanied in saturable absorption. Switching conditions for various combinations of absorption and refractive-index change are confirmed by FD-BPM simulation. As an experimental demonstration of saturable absorption in graphene, we discuss measured nonlinear absorption in a graphene-loaded waveguide. The saturable absorption and refractive-index change through vertically placed multilayered graphene sheets are also discussed based on reported experimental results.