Light scattering by dielectric and metallic cylindrical structures

Abstract

In recent years, many photonic components and devices have been developed using photonic crystals (PhCs) to take advantage of the bandgap effect and unusual dispersion properties. Although the principles of many devices can be illustrated by relatively simple designs obtained from physical intuition or simple models, practical applications often require a systematic optimization based on rigorous numerical simulations. A PhC device is usually only partially periodic, due to intentionally introduced defects. They can be either finite or infinite structures. The Dirichlet-to-Nuemann map (DtN-map) method is an efficient method for studying scattering problems of finite photonic crystal devices. It takes advantage of the partial periodicity of the structure. However, the DtN-map method requires boundary DtN maps to absorb outgoing waves. In this thesis, we construct boundary DtN maps by the method of fictitious sources. In comparison with previous works, our boundary DtN maps improve accuracy to a satisfactory level. We also present a boundary DtN-map approach using perfectly matched layers. With these boundary techniques, the scattering problems of finite PhC devices can be solved accurately and efficiently. In this thesis, we also analyze the transmission of light through a few one-dimensional arrays of metallic cylinders theoretically. It is found that for arrays with a subwave-length period and small gaps between nearby cylinders, high transmission is possible in two wavelength intervals, similar to the well-known extraordinary optical transmission (EOT) phenomenon in metal films. Furthermore, we develop an efficient method to analyzelight transmission through non-periodic arrays of metallic cylinders and find similar EOT phenomena in these structures. Moreover, we develop a DtN-map method with irregularly-shaped cells to analyze interpenetrating arrays of cylinders. For these interpenetrating problems, some existing methods have difficulties.

Date of Award	2 Oct 2013
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Ya Yan LU (Supervisor)