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Multi-photon Processes: Dynamics and Applications to Photonics and Biophotonics

Paras N. Prasad

Institute for Lasers, Photonics, and Biophotonics, University at Buffalo, State University of New York, Buffalo, NY

11.00am, Tuesday 26 March 2002, Seminar Room (AR103), Graduate Research Centre, Swinburne

Multiphoton Processes were predicted theoretically by Goeppert-Mayer in 1931 long before it was experimentally verified. However, until recently, it was perceived as of fundamental interest only because of its low photon conversion efficiency. Recent progress in molecular design of highly efficient two-photon materials has opened up new opportunities both for photonics and biophotonics applications. This talk will cover the fundamentals and dynamics of Two-Photon Processes and application to 3-D optical data storage, 3-D microfabrication and 3-D optical circuitry for telecommunications. The progress made in our laboratory to design and produce highly efficient two-photon materials will be presented. Very recently, we have also reported stimulated emissions produced by very efficient three-photon absorption. Another direction has been the study of two-photon processes on nanometer-size scale using photonics crystals and near field excitation. The use of two-photon polymerization in a near-field geometry has provided opportunities for nanofabrication Another type of multi-photon process studied in our group comprises sequential absorption in nanoparticles of rare-earth doped organic oxides.

Applications to biophotonics involving a new direction for Optical Tracking of cellular and therapeutic processes will be discussed. This approach will be illustrated with the application of two-photon confocal microscopy using fluorescent-labeled therapeutic agent to understand the cellular mechanism of chemotherapy. The application of multiphoton processes in photodynamic therapy of deep-rooted tumors is also pursued. A new concept developed by us is that of a nanoclinic for optically guided and targeted therapy.

The talk will conclude with a discussion of new opportunities in this field.

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