Waveguide dispersion in anisotropic optical waveguides

The method of shift formulas is employed to obtain approximate analytic expressions which can be used to calculate—with sufficient accuracy for practical applications—the waveguide and polarization dispersion of the dominant orthogonally polarized modes in anisotropic optical fiber waveguides. It is shown that the anisotropy of a dielectric in the transverse cross section and the ellipticity of the shape of this cross section (shape anisotropy) alter the waveguide dispersion of modes in such waveguides compared with an isotropic waveguide. In the case of waveguides which conserve the state of polarization of the transmitted signal the changes in the waveguide dispersion due to the transverse anisotropy of the refractive index are considerably greater than the changes due to the ellipticity of the shape of the transverse cross section of the waveguide. In a waveguide with a transverse anisotropy of the refractive index the maximum waveguide dispersion of two mutually orthogonal modes occurs at different frequencies.