All Optical Processing Device Utilizing Holographic Pyro-electro Optic Modulation
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Ducharme, S: AUTHOR [+2]
A device is disclosed for the production of dynamic holographic gratings in a pyroelectric material.
All Optical Processing Device Utilizing Holographic
A device is
disclosed for the production of dynamic
holographic gratings in a pyroelectric material.
which is both pyroelectric and electro-optic and
exhibits optical absorption can be made to diffract light by the
creation of a dynamic holographic phase grating by intersecting two
or more coherent optical waves in the material. The holographic
phase grating can be used to diffract, or deflect, one or more
optical "readout" waves which may include one of the original waves
as well as separate, relatively incoherent, waves.
works as follows. The input waves
interfere to form
bright and dark regions. The bright regions are locally heated by
absorption of the light and, through the pyroelectric effect (1),
these bright regions exhibit electrical polarization. The refractive
index of the (bright) regions with induced pyroelectric polarization
is altered according to the electro-optic effect (2), thus producing
a replica, or holographic phase grating, of the intensity of the
interfering optical waves. The holographic phase grating lasts only
as long as the original temperature perturbation produced by the
interfering coherent beams.
A key feature of this device is that the index
amplitude per unit energy density and the internal thermal relaxation
rate per square grating spatial frequency both depend upon the