Comparison of Stimulated Brillouin Scattering in Different Optical Fibres

The goal of this project is to model temperature dependent nucleation and growth rates of laser induced crystals in glasses. The laser at our disposal is a femtosecond laser with a power of 800mW, moving at a speed of approximately 20um/s. Several approaches are taken to the task of modeling, primarily based off Fourier’s heat equation – expanded to three dimensions. Equilibrium temperature is taken to be when heat loss to surroundings equals the heat gain from the laser, and boundary conditions are set at room temperature. Concessions are made to simplify to equation to a form which could be sufficiently approximated in Python. Variables such as specific heat capacity, thermal diffusivity, and others are taken to be constants when they are not. The derived equation is then iteratively applied across the spatial coordinates of the glass in question, with time a variable. The data obtained is then plotted as a 2D array with adjustable z-axis. The faster models are compared to a more exact solution and found to be sufficient in their capabilities to approximate temperature distribution. I would like to thank the National Science Foundation for presenting me the opportunity to conduct this research through grant PHY-1359195. Madison Brown, Lehigh University Summer 2017 REU Participant Qingguo Bai, Jean-Pierre Delville, Marie-Helene Delville, H. Daniel Ou-Yang