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When the cross-section of an optical waveguide is much smaller than the operating wavelength, unique materials and
structural dependent properties can be observed. In this regard silicon has been particularly attractive as the low-cost and
mature CMOS fabrication technology widely used in the electronics industry can be exploited. The high index contrast
of silicon allows light confinement in submicron size waveguides, along with the creation of very compact bends, to
allow increased functionality of photonic integrated circuits. A rigorously H-field based vectorial modal analysis has
been carried out, which can more accurately characterize the abrupt dielectric discontinuity of a high index contrast
optical waveguide. As a result, the full-vectorial H and E-field and the Poynting vector profiles are shown in detail. The
work done and reported reveals that the mode profile of a circular silicon nanowire is not circular and also has a strong
axial field component. Arising from the results of the analysis, the characteristics of single mode operation, the vector
field profiles, the modal ellipticity and the group velocity dispersion of this silicon nanowire both circular and planar are
presented. The modal hybridness and birefringence of rectangular silicon nanowires and slot-type waveguides are also
presented.
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