William Angerer - Department of Physics and Astronomy - University ...

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tionallinear microscopy is unable to resolve structural inhomogeneities. For example.
linear microscopy has serious limitations in samples such as polycrystalline films that
have a uniform index of refraction. In contrast, nonlinear optical processes are highly
sensitive to material symmetry, and therefore a greater variety of spatial inhomogeneities.
Nonlinear optical microscopy is also well suited to discriminate between
nonlinear and linear materials. 'rVe are attempting to exploit this sensitivity in order
to probe the nonlinear optical properties of carbon nanotubes on glass.
The synthesis of carbon nanotubes by Iijima [28] in 1991 has nurtured an exciting
field of research. One of the most interesting properties of carbon nanotubes is their
unique structure. Carbon nanotubes are fullerene related structures that consist of a
graphene cylinder closed at each end with a cap. A (10,10) nanotube has a diameter
of 1.-1 nm and may have a length of a few microns. The nanotubes are packaged
together to form carbon nanoropes, and the raw synthesized material consists of
tangled carbon nanoropes and other carbonaceous materials. Typically, the tubes
and ropes are produced by a current discharge between carbon electrodes [29]. \Vhile
intensive experimental effort has been directed toward the growth of nanotubes and
the characterization of the structural and electrical properties of carbon nanotubes.
the linear and nonlinear optical properties of carbon nanotubes have been largely
unexplored.
Our nonlinear optical microscopy of carbon nanotubes was motivated to under-
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