NOVEL OPTICAL WAVEGUIDE ANALYSIS METHOD USING FOURIER TRANSFORM.

A precise design method for waveguide devices such as Ti:LiNbO//3 switch/modulators has been required. These functional waveguides propagate not only guided-mode but also radiation-mode light because of their complex shape and refractive index change profile. The analysis method which can treat radiation-mode light was developed by Feit et al. for multimode fiber and applied to waveguide by Roey et al. We develop a novel analysis method which can treat even radiation-mode using Fourier transforms by introducing virtual modes in a virtual waveguide. The advantage of this method is that the analytical procedure is simplified by changing differential equations into different equations. This method has the potential of high approximation accuracy and design effectiveness for practical waveguide devices.