Femtosecond Optical Interactions in Glasses

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9612255 Wise A multi-disciplinary investigation of the interactions of ultrashort light pulses with optical glasses is proposed by a team of scientists from Cornell University and Corning, Incorporated. The primary goal is to develop a thorough and systematic understanding of the fast optical nonlinearities that are the physical basis for a wide variety of optical devices and systems. Third-order nonlinearities excited by laser pulses consisting of only a few cycles of the electromagnetic field will be studied in a variety of experimental glasses. Since glasses are typically Raman-active, the nuclear contribution to the nonlinear optical response must also be considered. The absorptive and refractive third-order nonlinearities will be measured with 10-fs pulses, with the specific goal of isolating the electronic and nuclear contributions to the nonlinear response. Using the knowledge of individual processes gained in these studies, the nonlinear and dispersive propagation of ultrashort pulses in glasses will be investigated theoretically and experimentally. Experiments will utilize pulse durations ranging from 10 to 200 femtoseconds in a variety of glasses to study the effects of group velocity dispersion, stimulated Raman scattering, multiphoton absorption, the finite relaxation time of the electronic nonlinearity, and the breakdown of the slowly-varying envelope approximation. A secondary theme of the proposed work is the relation between the local structure of a glass and the relaxation of vibrational and electronic excitations in the glass. The dephasing of vibrational modes and the relaxation of electronic impurities excited by short optical pulses will be studied using both time- and frequency-domain experiments; in each case the results will be correlated with the local structure. Graduate students involved in this work will participate in an innovative education program that includes a multi-disciplinary course curriculum and assignments to work on t he synthesis and characterization of glasses at the Corning location for one month each year. This experience will provide the students with a broad foundation in the optical physics and material science of glasses as well as giving them substantial exposure to industrial research. ***