Beam propagation and mode coupling study in a coupled waveguide structure by using scalar finite element method

Here we present the propagation of pulse in a coupled waveguide structures. Finite element method has been effectively applied to analyze the closely coupled waveguide structure. The mode coupling phenomena is well described in this paper. It is demonstrated that there are substantial amount of power exchange takes place between various modes. We excite the structure with original mode pattern which can be well approximated by slightly deviated Gaussian shape pulse. Then we apply the mode propagation concept to estimate the mode beating phenomena in coupled structure. The effect of waveguide separation is well demonstrated by using examples. We too derive the Fresnel equation and discuss a solution strategy in terms of the finite element method. We apply the transparent boundary condition to avoid the unwanted reflections from the artificial computation windows.