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Department of Electrical and Computer Engineering
Assistant Professor Kriehn
Faculty Development - Read-Write Multiplexing for Dynamic Holography
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.