<title>Integration of electro-holography in next-generation optical cross connects</title>

Abstract

Abstract This paper discusses an all-optical switching device for routing sign als in a WDM system based on a technique known as Electro-holography. The device features a photorefractive crystal with a hologram affixed in its crystalline structure. Upon receiving the correct stimulus, the device controls the index of refraction of the crystal and results in a diffraction of an input data signal to the correct output fiber based on the hologram’s coding. When integrated in cross connect devices, WDM systems are projected to have faster response times and switching speeds resulting from the immense recording capabilities associated with an HOE. Key words : OCC (Optical Cross Connects), Photorefraction, Electro-Optics, Electro-Holography, HOE (Holographic Optical Elements), Pockels Effect INTRODUCTION The ability to switch between communication channels (or channel cross-connecting) in an effort to maintain and/or increase the bandwidth of a fiber is a fundamental task of WDM systems. Typically, this is performed by a hybrid technology approach where optical data is converted to electronic data when switching is required. Once forwarded to its new location in the WDM system, this data is then electronically converted back to optical data. The problems associated with this electronic conversion are noise, cross talk, etc. These anomalies require these systems to utilize large portions of the fibers bandwidth for channel routing as opposed to data transmission. As a result, it is bene ficial to retain the original optical properties for more efficient data transmission. The need for the electronic data conversion is being eliminated by utilizing an optical switch known as optical cross-connects (OCC). There are a few variations in the method of optical cross-connecting, however, of the more promising is the solid-state optical switch utilizing a holographic optical elements (HOE) recorded on aphotorefractive crystal by a technique known as Electro-holography. Essentially, this technique will embed a hologram within a birefringent crystal that becomes re flective, absorptive, polarized, etc. to a specific wavelength upon receiving the correct i nput para meter. A number of cry stals are suitable for this technology. Among these are: barium titanate BaTiO