<span>Background of the invention: 1. Field of the Invention This invention relates to the materials and a method for fabricating multilayer nonlinear dielectric optical structures from polymeric materials. In particular, the present invention relates to multilayer materials characterized by a modulation in the nonlinear refractive index in the direction normal to the surface of the layers. 2. Discussion of the Related Articles: The propagation of electromagnetic waves through periodic structures consisting of layers of materials with an intensity-dependent dielectric constant has been studied both theoretically and experimentally. A historical review was reported by Brown et al (T. G. Brown and B. J. Eggleton, Optics Express 3, 385 (1998)). The transmission and reflection properties of such structures are strongly modulated by the intensity of the incident light. The optical response of such structures can include optical switching, optical limiting, optical bistability and some remarkable pulse propagation effects including transverse pattern formation. Some optical effects have been shown experimentally using, for example, colloidal arrays (C. Herbert and M. Malcuit.; Opt. Lett. 17, 1037 (1992)), semiconductor multilayers, silicon-on-insulator waveguides (N. D. Sankey, D. F. Prelewitz and T. G. Brown; Appl. Phys. Lett. 60, 1427 (1992)) and fiber gratings (S. Larochelle, Y. Hibino, V. Mizrahi and G. Stegeman; Electron. Lett. 26, 1459 (1990)). An organic nonlinear dielectric stack was reported by </span><span>Norwood et al. in 1992 using a silicon naphthalocyaine-poly(methyl methacrylate) structure made by spin coating sequential layers (R. A. Norwood et al.; Opt. Lett. 17, 577 (1992)). However, only a few layers are possible with a spin coating technique. Norwood et al in the above publication reports only 23 layers. The preparation of layered structures of polymeric materials by coextrusion has been used to prepare materials with combinations of physical properties. Such materials having three to seven layers are commercially available. More recently, the development of layer multiplying dies has allowed the preparation of multilayer polymeric materials with hundreds or even thousands of layers (E. Baer, J. Kerns, and A. Hiltner; "Processing and Properties of Polymer Microlayered Systems": NATO-ASI on Structure Development During Polymer Processing, Guimaraes, Portugal, May 17-28, (1999)). The total thickness of the structured material is controlled by the feed ratio. With thousands of layers, individual layer thickness down to 30 nanometers or less can be achieved. Recent processing improvements and improvements in the multiplying elements allow layer thickness to be constant within a few percent. Optical properties of nonlinear dyes have led to the development of materials that have a large nonlinear absorption and/or a large nonlinear refraction coefficients (J. S. Shirk, R. G. S. Pong, F. J. Bartoli, A. W. Snow; Appl. Phys. Lett., 63, 1880 (1993)).http://www.google.com/patents?vid=USPAT6582807</span>

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