Light Waves in a Composite of Cylindrical Nanoinclusions in Passive and Active Host Matrices
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Date
2014-06
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Addis Ababa University
Abstract
In this thesis work, we have studied the optical properties of a composite with metal coated di-
electric cylindrical nanoinclusions / pure metal cylindrical nanoinclusions in passive and active
dielectric host matrices. In order to compare results, we have also brie
y discussed optical prop-
erties of a composite with spherical nanoinclusions in passive and active dielectric host matrices.
One of the optical properties of the composite we have investigated by this work is the lo-
cal eld enhancement factor at the core of the inclusions. The obtained result shows that for a
composite of metal covered dielectric inclusions in passive host matrix there are two maximum
values of the local eld enhancement factor at two di erent resonant frequencies. For composite
with dielectric covered metal inclusions only one peak of local eld enhancement factor deter-
mined. We have also found that for a composite with pure metal cylindrical inclusion there is
only one maxima of the local eld enhancement factor.
In this work, the second main target of study interest was to determine the group velocity
of narrow light wave packet that propagate in the overstated composites. We have determined
that wave can travel with group velocity much slower than the speed of light in vacuum and
faster than the speed of light in vacuum. Furthermore, we have found light waves that propa-
gates with negative group velocity through the composite. In passive host matrix the light pulse
seen absorbed within a very small distance when compared to the distance it travels in active
host matrix. Hence the problem of absorption considerably reduced by using active host matrix
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Keywords
Light Waves in a Composite