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Final Examination of Ramy El-Ganainy for the degree of Doctor of Philosophy in Optics
Tuesday, August 25, 2009 3:00 PM to 5:00 PM CREOL Room 102
Dissertation title:
OPTICAL NONLINEAR INTERACTIONS IN DIELECTRIC NANO-SUSPENSIONS
Abstract:
Light-matter interactions via radiation forces play nowadays a crucial and central role in several areas of physics, chemistry and biology. One such example is the rich interdisciplinary field of optical traps or tweezers first pioneered by Ashkin and colleagues. In these early studies the optical self-focusing and four-wave mixing response of colloidal artificial nonlinear systems was also explored in a series of experiments. In such settings the optical nonlinearity is a direct outcome of the electromagnetic gradient force.
In this work, optical nonlinear interactions in dielectric nano colloidal systems were investigated theoretically. Based on the refractive index contrast between the nano-spheres and their host liquid, it is shown that the nonlinear response can be saturable or super critical. Modulational and transverse modulational instability were studied in all different cases and new regimes of instabilities were identified. Many-body effects on the nonlinear interactions were also considered and a nonlinear evolution equation based on the non-ideal gas equation of state was developed with good agreement between theory and previous experimental work being demonstrated. In the above mentioned model, the nonlinear response term does not appear explicitly in the evolution equation and hence one can not obtain the system's Hamiltonian. In order to overcome this obstacle we introduced the concept of shifted Hamiltonian and showed how to obtain its value in both one and two dimensional geometries.
Major: Optics
Educational Career:
Committee in Charge:
Approved for distribution by Dr. Demetrios Christodoulides, Committee Chair, on August 12, 2009
The Public is welcome to attend
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