Analysis of nonlinear three-layer optical waveguide

Optical waveguides are characterized by regions of high refractive index bounded by regions of lower index regions and can be categorized as planar, channel, and fiber guides. Monochromatic Laser light is used as the signal carrier through the optical waveguide. If the strength of Laser light is increased, the repeater distance of an optical fiber network can be increased. So to obtain high intensities, it is usually necessary to focus laser beams into the higher index guided region of the optical waveguide where signal processing will take place. However, high laser intensity within a small guided region will cause nonlinear behavior of the waveguide. In this research work the refractive index of the waveguide is assumed to be the function of the square of electric field. Various guided structures are analyzed considering nonlinear refractive index. First the eigenvalue equation is solved to determine the confined guided modes and then the propagation of these modes through different structures are found using Beam Propagation Method (BPM). Since the efficiency of a nonlinear interaction depends at least linearly, and in many cases quadratically, on the interaction distance, clearly there is a trade-off in the efficiency between high intensity and interaction length.