Choudhury, P K; Roger, Lessard S(Microwave and Optical Technology Letters, January 20, 2002)
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Abstract:
An attempt is made to determine the relative power
distribution in a step-index parabolic cylindrical waveguide (PCW) with
high deformation across the direction of propagation. The guide is
assumed to be made of silica. The scalar field approximation is employed
for the analysis under which a vanishing refractive-index (RI) difference
in the waveguide materials is considered. Further, no approximation for
folds- is used in the analytical treatment. Due to the geometry of such
waceguides, PCWs lose the well-defined modal discreteness, and a kind
of mode bunching is observed instead, which becomes much more
prominent in PCWs with high bends. However, with the increase in
cross-sectional size, the mode-bunching tendency is slightly reduced. The
general expressions for power in the guiding and nonguiding sections are
obtained, and the fractional power patterns in all of the sections are
presented for PCWs of various cross-sectional dimensions. It is observed
that the confinement of power in the core section is increased for PCWs
of larger cross-sectional size. Moreover, a fairly uniform distribution of
power is seen over the modes having intermediate values of propagation
constants