A Fourier transform technique, the Free Space Radiation Mode (FSRM) method, is described for the analysis of optical waveguide structures. The method is a semi- analytical approach and is based on the assumption that the radiation modes of a waveguiding structure propagate in a region of uniform refractive index. It is therefore ideally suited to structures in which a small index variation in the transverse direction exists. In many cases, the method can be considered an alternative to more computationally intensive methods and is a suitable CAD tool, finding application in a design environment. The FSRM method is initially developed to analyse waveguide discontinuities with application to waveguide facets in the one dimensional slab waveguide case. In two dimensions it is then applied to the analysis of scalar, polarised and vectorial modes in longitudinally invariant buried rectangular waveguides. The natural extension to fully three dimensional structures is then made with the analysis of the reflectivity of a waveguide incident normally upon a facet. This is followed by a study of propagation in a range of practical optical waveguides. Formulations are compared with benchmark methods and are shown to be extremely accurate.
- Pub Date:
- Physics: Optics, Engineering: Mechanical