Method and system for maintaining and controlling the signal-to-

Details Method and system for maintaining and controlling the signal-to- Method and system for maintaining and controlling the signal-to-

1995-09-15

1997-11-04

Dzierzynski, Paul M.

Optical: systems and elements

Holographic system or element

Having particular recording medium

359 3, 359 5, 359 25, G03H 102

Patent

active

056846126

ABSTRACT:
A hologram with a dynamically controlled diffraction efficiency and enhanced signal-to-noise ratio is recorded in ferroelectric photorefractive materials, such as strontium barium niobate (Sr.sub.x Ba.sub.1-x Nb.sub.2 O.sub.6) (SBN), BSTN, SCNN, PBN, BSKNN, BaTiO.sub.3, LiNbO.sub.3, KNbO.sub.3, KTN, PLZT and the tungsten bronze family. The diffraction efficiency of the hologram is dynamically controlled by applying an electric field along the polar axis of the ferroelectric photorefractive recording medium. Electrically controlled diffraction is used in conjunction with hologram fixing and operation of the material at a temperature in the vicinity of or above its Curie temperature to additionally provide prolonged, low-noise readout. The general methods for recording and reconstructing a hologram (or a set of multiplexed holograms) using these techniques is disclosed. A plurality of configurations employing the improved hologram are disclosed, including an optical crossbar switch in guided-wave and free-space formats that can function as a component in a variety of parallel optical processing systems, a reconfigurable dynamic wavelength filter, and a page-based holographic data storage system.

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