Date of Award
Master of Science (MS)
This thesis describes modulation instability of a broad beam of partially spatially incoherent laser light propagating in a photopolymerisable organosiloxane. Refractive index changes due to photoinitiated free-radical polymerisation lead to a nonlinear regime in which even weak perturbations in the optical field become amplified. These trigger the spontaneous division of the beam into multiple self-trapped filaments of light. By tuning the spatial coherence of the beam, it was possible to vary the diameter of the self-trapped filaments. Quantitative analyses showed that the relation between filament diameter and spatial incoherence was consistent with a previously developed theoretical model. Because refractive index changes in the photopolymer are irreversible, modulation instability led to a permanent array of self-induced waveguides. In this way, it was possible to control the dimensions of the spontaneously formed polymer microstructure by tuning the incoherence of the optical field.
Shimmel, Whitney E., "Controlling Polymer Microstructure Through the Coherence of Light" (2009). Open Access Dissertations and Theses. Paper 4138.
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