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Photosynthesis
New
Liquid Crystal Composite Materials
for Photorefractive Applications
The photorefractive effect is an energy efficient method through
which image storage and retrieval can occur with outstanding
image quality and high density. The photorefractive effect results
from optically induced directional charge transport within the
material. When the charges trap, an electric field is produced
which modulates the material’s index of refraction. When this
effect is properly harnessed through a laser induced grating,
image storage and retrieval can occur. Commercially available
photorefractive materials currently available consist of inorganic
ferroelectric crystals which are expensive and time consuming to
grow. We have shown during this project that liquid crystals
represent a simpler and more economical alternative to presently
available materials. Furthermore, liquid crystals allow for greater
versatility due to the ease with which different chromophores
can be utilized to “sensitize” the material to different laser
wavelengths. These materials also possess significant advantages
for dynamic holography due to their low photon flux requirements
and ease of hologram erasure.
Several of the goals of the project have been accomplished.
We have succeeded in aligning liquid crystals through the
application of magnetic fields, providing superior grating
resolution compared to liquid crystals aligned solely through
surfactant techniques. We have also created liquid crystals that
operate in the near infrared spectral region, which is required
for studies related to imaging biological tissue. This was
accomplished using substituted phthalocyanines as electron
donors and pyromellitimide as an electron acceptor. We have
also been able to develop polymer/liquid crystal composites
whose photoconductive mechanism occurs in large part by
intrachain electron hole transport, rather than solely through
ion diffusion. This permits faster formation of the photorefractive
grating at smaller fringe spacings.
Return to Photosynthesis
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Glassblowing
Interfacial
Processes
Radiation
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Photosynthesis
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Materials Growth Facility
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