@mastersthesis {9994,
	title = {Nonlinear Optical Waveguides from Dilute Composites Consisting of Polymer with Partially Aligned Nanorods},
	year = {2012},
	type = {MSc thesis},
	abstract = {The expected permittivity and third order nonlinear susceptibility, of a low filling fraction\&nbsp;composite consisting of semiconductor nanorods dispersed in a polymer host are derived,\&nbsp;using the Maxwell-Garnett model for anisotropic nonlinear inclusions. The semiconductor\&nbsp;nanorods are modeled both as prolate spheroids and more realistic capsule shapes. A new\&nbsp;generalized model is presented for various nanorod axis orientation statistics, achieved by an\&nbsp;aligning electric field. The angular distribution function of the nanorods is calculated for\&nbsp;nanorods with a permanent electrical dipole moment, which assists the alignment of the\&nbsp;nanorods. Using the angular distribution function, the composite macroscopic characteristics\&nbsp;are found for a composite with random orientation, partially aligned and nematic array\&nbsp;nanorods. As the alignment field strength increases, the composite optical propertiesasymptotically converge towards the nematic case. Different parameters relate to the\&nbsp;nanorods geometry are examined, concluding that the main parameter influencing the\&nbsp;alignment is the single NR volume, while for the nematic array the single nanorod axes\&nbsp;aspect-ration is the major parameter. Due to the symmetry of the nanorods, the composite\&nbsp;characteristics depend on the polarization of the optical electrical field, with a symmetry that\&nbsp;resembles a uniaxial crystal.A nonlinear waveguide with a core made of such a composite is simulated, in order to find\&nbsp;the nonlinear parameter of the waveguide. The model takes into account two electrodes for\&nbsp;the alignment process, far enough from the waveguide core, in order to avoid losses to the\&nbsp;optical mode. Significant optical response can be achieved even for randomly oriented\&nbsp;nanorods composite, with a nonlinear parameter of 68(W{\texttimes}m)-1. The alignment process\&nbsp;increases the nonlinear parameter significantly even at elevated temperature that are needed\&nbsp;for polymerization of the polymer host, typically 150oC. Aligning field strength of 107 V/m\&nbsp;results with very high value for the nonlinear parameter {\textendash} 120(W{\texttimes}m)-1, much higher than\&nbsp;ordinary glass based nonlinear optical fibers, that result with nonlinear parameter up to\&nbsp;50(W{\texttimes}m)-1.},
	url = {http://hufind.huji.ac.il/Record/HUJ001748356},
	author = {Yedidya Lior}
}
