Objectives
Photorefractive
crystals are useful for spatial-temporal information processing of
coherent optically-modulated signals due to the real-time, read-write
capabilities of the holographic medium. When used
to write volumetric holographic gratings for real-time applications,
it is necessary to isolate the recording, or writing beams, from the
diffracted read-out beam. This isolation is an
extremely
important factor in adaptive feedback systems because it determines
the amount of feedback gain, and therefore the jammer null depth,
of, say, an optically-processed phased-array antenna. A
special (and extremely powerful) geometry, called the
parallel-tangents, equal-curvature condition enables the writing of
wide-angular aperture holograms using one polarization, and efficient
diffraction of the entire angular aperture using an
orthogonally-polarized beam using a different angle with respect to
the writing beams. Although simulations and experiments verifying
the theory have been performed when one writing beam contains a wide
angular aperture, a theoretical optimization has never been performed
when both writing beams contain a large angular aperture. The
objective of this proposal, therefore, is to perform a numerical
optimization of the geometry, the results of which may allow for future
publication.
