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Proceedings Paper

Genetic algorithm for design of reflective filters: application to AlxGa1-xN-based Bragg reflectors
Author(s): E. Herbert Li; Aleksandra B. Djurisic; Nenad K. Bundaleski
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Paper Abstract

A genetic algorithm (GA) with adaptive mutations has been employed for the design of Bragg reflectors. The algorithm enables three different design types a) composition and thickness of two layers are chosen and the pair is repeated b) two compositions are chosen for the two alternating materials, and thickness of each layer is optimized c) composition and thickness of each layer are optimized. In all cases, the wavelength and composition dependence of the index of refraction is taken into account. Also, it is possible to impose constraints on the composition difference of the neighbouring layers, either with a penalty function or with narrowing the boundaries for possible compositions. This feature is important because the large lattice mismatch between GaN and A1N can cause poor surface morphology, so measured reflectivity would be lower than the calculated one due to the surface roughness. The algorithm enables finding the optimal design for two chosen incident and final media, and it is capable of taking into account the existence of a finite, optically thick substrate. We have investigated two systems: air/sapphire/A1xGa1-xN reflector/GaN and GaN/A1xGa1- xN/air.

Paper Details

Date Published: 19 October 2000
PDF: 8 pages
Proc. SPIE 4094, Optical and Infrared Thin Films, (19 October 2000); doi: 10.1117/12.404759
Show Author Affiliations
E. Herbert Li, Univ. of Hong Kong (United States)
Aleksandra B. Djurisic, Univ. of Hong Kong (Hong Kong)
Nenad K. Bundaleski, Institute of Nuclear Sciences (Serbia)

Published in SPIE Proceedings Vol. 4094:
Optical and Infrared Thin Films
Michael L. Fulton, Editor(s)

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