Propagation of normal modes in multilayer optical waveguides. III. Waveguides with negative dispersion and strong higher-order filtering

An analysis is made of five types of circular three-layer dielectric waveguides for the optical range. It is shown that the use of an additional (second) cladding makes it possible to construct single-mode waveguides with large transverse dimensions, strong filtering of higher stray modes because of deliberately induced thermal or radiation losses, and a negative waveguide dispersion which can partly compensate the positive dispersion of the waveguide material. Estimates are obtained of the signal distortion in single-mode and multimode operation of such waveguides.