Masters Thesis

Nonlinear propagation of light through biological media

This thesis discusses three experiments on light propagation and beam dynamics in biological media. In the first, a gaussian laser beam transmits through a solution of human red blood cells (RBCs) in a guided manner with no photodamage. The self-trapping and deep penetration of a visible laser beam in RBC suspensions may be useful in medical diagnostics. In the second, we develop a new type of optical tweezers with lateral pulling forces, which allows enhanced control of biological samples with complex geometric shapes. We have demonstrated the Tug-of-War tweezers effectively hold and stretch bacterial cells of different shapes and sizes. The strong lateral pulling forces may allow Tug-of-War tweezers to be useful in biofilm studies. In the third, we observe rogue wave events in RBC suspensions driven by light scattering and dynamic forces. We also observe rogue waves in colloidal suspensions of polystyrene microspheres. The data suggest the number of rogue wave events, in both systems, reaches maximum at a certain particle concentration.

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