|M.Sc Student||Yoav Hazan|
|Subject||Light induced shock-wave interaction in opaque suspensions|
|Department||Department of Physics||Supervisor||? 18? Segev Mordechai|
|Full Thesis text|
Light-Fluid interactions give rise to physical phenomena that are fundamentally different from those encountered when light interacts with solids. The mobility of the fluid, the possibility to optically induce deformations in the flow field, the ability to have small particles suspended in the liquid, the important role of diffusion and convection in transporting substance, and the large-scale heterogeneities emerging when fluid interacts with light - all contribute to the variety of nonlinear interactions unique to light-fluid systems. Examples of such phenomena are optically induced unidirectional flow, to optical-force induced self concentration of substance in colloidal suspensions and more.
In this thesis, I have studied a system of high intensity light propagating in highly scattering suspensions and investigated the phenomena arising when light and fluid interact with one another, forming a complex nonlinear dynamical system. This work contributes to the physical understanding of the interaction between high intensity light fields with highly scattering suspensions. The key scientific issue investigated throughout this thesis is the interaction between two light-induced shock waves in the density of particles suspended in the liquid.
I studied experimentally the nonlinear interaction-collision between two light-induced shock waves of nano-particles in highly scattering (opaque) suspensions, observing the formation of domain walls between the two shock waves. I find that the interaction is dominated by the lateral offset between the input beams and the optical power of the input beams. The interaction of beams with a lateral offset creates shock-fronts, which transforms into unidirectional circulation whose direction is determined by the lateral offset between the input beams. In the case of a centered heads-on collision interaction, the shock waves give rise to a long-lived transverse domain wall, which is sensitive to very small asymmetry in the input beams. This work advances in the ability to controllably manipulate nano-particles in a highly scattering suspension, giving rise to multiple applications such as micro-fluidic controlled mixing, micro-fluidic enhanced chemistry, light induced shock wave filtration, and on-chip diagnostics for opaque suspension.