Applications of Photorefractive Materials

To date most of the polymeric materials have demonstrated potential rather than acmal commercial applications. The two-beam coupling behaviour has obvious applications in real-time optical processing and holographic data storage. 

---

Potential applications of photorefractive materials are manifold. To date, demonstrated effects include real time holography, correlation filtering, and various "novelty filter applications, one of which is the development of a microscope which distinguishes moving objects (such as living cells) from a stationary background.(149) The latter application employed BaTiC>3 as the active material. 

L Solymar, DJ Webb, A Grunnet-Jepsen. In A Hasegawa, M Lapp, BB Snavely, H Stark, AC Tam, T Wilson, eds. The Physics and Application of Photorefractive Materials, Oxford Clarendon Press, 1996. 

There are other applications of photorefractive materials that have been investigated, including associative optical memories that identify a clear image from a corrupted input [1], novelty filters to detect only changing features in an image [2], and neural networking in analogy with the human brain [3],... 

L. Solymar, D. Webb, A. Grunnet-Jepson, The physics and applications of photorefractive materials, OUP, Oxford, 1996, Chap. 4. 

Solymar, L. Webb, D.J. Gmnnet-Jepsen, A. In The Physics and Applications of Photorefractive Material, Oxford, U. K., 1996. 

L. Soljrmar, D. J. Webb, and A. Grunnet-Jepson, The Physics and Applications of Photorefractive Materials, Clarendon Press, Oxford, 1996. 

More recently the promising range of applications for photorefractive materials has motivated the rapid development of amorphous, organic materials with a strong photorefractive response [5]. Here the chemical composition of the materials may be varied with relative ease and the opportunity to compare materials from different sources should exist. The various processes necessary for photorefraction may be obtained by a single material, or many different molecular species may be mixed in a composite to provide the range of properties needed. These amorphous materials do not have a well-defined mobility for the photogenerated holes that... 

Charge transfer NLO polymers offer the promise of truly unique properties properties that mimic the performance of photorefractive materials, but on ultrafast (picosecond) time scales. Such materials would enable ultrafast photonic applications (e.g. ultrafast optical switching and ultrafast image processing) that are impossible today with any known class of materials. 

The present 10 volume handbook has a much broader scope. It includes semiconductor materials, quantum wells and quantum dots, liquid crystals, conducting polymers, laser materids, photoconductors, electroluminescent and photorefractive materials, nanostructured, supramolecular, and self-assembled materials, ferroelectrics, and superconductors. Applications of these materials in photoconductors, optical fibers, xerography, solar cells, dynamic random access memory, and sensors are described. The Handbook contains contributions by 180 leading experts from 25 different countries. It truly represents the worldwide research efforts and results that support the global market of optoelectronics. All scientific and technical workers in this broad field are indebted to the contributing authors, the editor and Academic Press for publishing this comprehensive handbook for the new millennium. It will support further growth in a field that already has surpassed my wildest expectations of 40 years ago. 

Applications of these materials are oriented toward the development of hybrid photochromic films for waveguides [87], high refraction index for LED encapsulation [283], or materials showing holographic as well as photorefractive properties [284]. 

In addition to their use as photoreceptors, these materials are of interest for a wide range of other electronic applications. Of these, electroluminescent, photorefractive, photovoltaic, and transistor devices are the most commonly... 

Earlier work on photorefractive materials was centered on the discovery of the properties of the phenomenon in optical crystals, most notably lithium niobate, strontium barium niobate, and barium tantalate. Both the mathematics of the theory of photorefraction outlined above and its application to these materials and... 

P. Gunter and J. P. Huignard, editors. Photorefractive Materials and Their Applications, 1, Basic Effects, volume 113 of Springer Series in Optical Sciences. Springer Verlag, Berlin, 2006. 

For several decades, the fields of photoconducting (75) and purely electrooptic polymers (74) have been very active but had almost no direct overlap. With the development of photorefractive polymers in the early nineties, the knowledge of these two research areas could be combined and has led to a rapid improvement of the performance of existing photorefractive polymers. The photorefractive polymer composite DMNPAA PVK ECZ TNF (DMNPAA 2,5 -dimethyl-4-(p-nitrophenyl-azo)anisole PVK poly(N-vinylcarbazole) ECZ N-ethylcarbazole TNF 2,4,7-trinitrofluorenone) we developed recently (P) has reached a level of performance that competes with that of the best inorganic photorefractive crystals (77,72). With the recent progress achieved in the development of new chromophores for electro-optic applications (75), the efficiency of these new materials is expected to be significantly further improved. 

---