Tube Waveguide for Optical Transmission

Dielectric optical waveguides have become interesting since it has been demonstrated that the losses of dielectric materials can be quite low. 1-3 The conventional optical fiber waveguide consists of a solid dielectric core surrounded by a dielectric material with lower refractive index. This structure has the advantage of being particularly simple. In this paper we analyze a different type of dielectric optical waveguide. Our structure consists of a dielectric tube which is filled and surrounded by dielectric material with lower index of refraction. Such structures have been analyzed before. 4 A complete discussion of and references to the literature can be found in Ref. 5. However, the exact analytical treatment is extremely complicated so that the resulting theories are hard to apply to practical situations. Recently A. W. Snyder 6 has shown that the analysis of the conventional optical fiber waveguide becomes much simpler if one assumes that the difference of the refractive indices of core and cladding material is only slight. D. Gloge 7 has developed Snyder's theoretical work even further. On the basis of this simplified method of analysis, it is possible to treat rather complicated optical waveguide structures more simply and still obtain results that are applicable to most cases of practical interest. The simplification that results from the assumption of only slight index 423