Optical Waveguides

Abstract

Optical waveguides are important to amplify light efficiently by confining light to the active layer. This chapter explains propagation modes by both geometrical optics and wave optics. In geometrical optics, Snell’s law is used to derive conditions to obtain radiation modes and guided modes. An eigenvalue equation, which shows a transverse resonance condition, is given by using Fresnel formulas and changes in the optical phases at boundaries accompanying total reflection. Effective refractive index and optical confinement factor, which are key parameters to design semiconductor lasers, are defined. To design or analyze optical waveguides, three-layer model and multiple-layer model are introduced. The three-layer model is useful to understand the basics of optical waveguides; the multiple-layer model is a powerful tool to design or analyze two-dimensional optical waveguides.