Coupled mode analysis of tapered optical waveguides

Abstract

In integrated optics, tapered optical waveguide-based devices are in need, especially as end-to-end couplers between different devices and optical fibres. Light propagation to tapered waveguides is characterized by mode perturbation and loss arising due to coupling of guided mode power into radiation modes. In this paper, coupled mode theory of dielectric optical waveguides is developed specially to include coupling between guided and radiation modes. A two-dimensional tapered structure with a quadratic taper function along propagation axis and a parabolic refractive index profile for transverse cross-section is solved analytically. Numerical calculations In the case of LINb03-based device, for the power variation of the guided mode, reveal a loss in the range 1-5 dB Within a propagation distance of 100m.