9624921 Law The soaring increase in network traffic has overwhelmed the transmission capacity of current communications systems that use electronic switches and copper wires. The use of optical fibers, switches and modulators, components of all-optical networks, could equalize not only this disparity but also provide a gigantic increase in the speed of the information superhighway. This proposal describes novel approaches to build these optical components. All-optical switching and modulation enable one light beam to control the orientation as well as intensity of another light beam, and are hundreds of times faster than electronic processes. What is more, a light beam can guide another light beam, which follows the guiding beam's "footprints"-a process called light-induced waveguiding. These waveguides are produced by special nonlinear waves called optical vortex solitons. These solitons are peculiar vortex-like pulses that retain their shape and height after traveling long distances. Vortex solitons form in selfdefocusing Kerr nonlinear media when their tendency to spread (diffraction) is counterbalanced by their ability to change the refractive index of the media (Kerr nonlinearity). Recent experiment has demonstrated the light guiding capability of vortex soliton in this kind of medium. Optical transistor effect is another recent experimental result that reveals the potential application of vortex solitons in optical switching and modulation. Manipulating the size of a vortex soliton, another light beam (gate signal) can control the guiding efficiency and sensitivity of light-induced waveguide. As a result, a guided beam is modulated as well as amplified by the gate and guiding beams. The proposed study will establish the theoretical basis for light-induced waveguides, modulators and switches as well as simulate their actions computationally. Particularly, the propagation dynamics of vortex solitons in a CW laser beam as well as in a laser pulse will be investiga ted. This study will concentrate on the interactions among vortex solitons themselves as well as vortex solitons with other light pulses. These interactions are crucial to practical applications, such as optical interconnections. Vortex solitons not only have tremendous application potential, but also constitute a new frontier for the exploration of vortex physics. This may lead to discovery of novel phenomena that will find applications in other areas. The outcomes of this project will result in a general simulation package for designing nonlinear devices. Simulation results will be verified by various numerical methods as well as experimental data provided by co-works at Worcester Polytechnic Institute, Naval Research Laboratory and Wright Laboratory. A well-balanced education for engineering students should consist of computational and experimental training. One of the proposed educational activities involves the use of computer as a tool for learning and communication in the undergraduate Electromagnetics class. Computer can enlighten students on those abstract theories by presenting results on visual display. As a communication tool, computer becomes another channel for a two-way discussion between an instructor and students. This will be achieved by setting up an electronic bulletin board and a home page for the class. The role of computer in graduate research is even more sign)ficant. Graduate training will include extensive exposure to different numerical techniques and development of analytic sense. Graduate student, as a researcher, should be capable of searching for information and disseminating research results timely. Again graduate students will receive in-depth training on using computers for communication. For experimental training, a graduate student exchange program will be set up with Worcester Polytechnic Institute which has a nonlinear optics laboratory with state-of-the-art equipment. At UWM, an optics laboratory will be set up for three opti cs courses-optical communication, laser and nonlinear optics-with the help of graduate students who participate in the exchange program. This laboratory will also be used to verify numerical results for the research project. Experiments for the three courses will focus on practical issues and design techniques as well as current research topics. The list of experiments will be updated to keep abreast with technology. The proposed optics laboratory will be a magnet for attracting students to involve in optical research. The intent of the experiments in the three optics courses is to introduce research activities to undergraduate students. Computational training is another component in the proposed research and education plans. Computer will be used heavily as communication tool and learning aid for both education and research. ***
