Defect modes in metallo-dielectric photonic crystals

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We propose to study and control photonic defect modes in plenar metallo-dielectric photonic crystals. The photonic crystal structures consist of arrays of gold and silver nanoparticles deposited on dielectric surfaces using electron beam lithography. Defects will be intentionally introduced into the arrays, and the resulting photonic defect modes will be experimentally studied using advanced optical techniques with wavelength and sub-wavelength spatial resolutions. Light-scattering from individual defects will be measured and used to characterize the spectral properties and the symmetries of the defect modes. The spatial mode distribution and optical field enhancement associated with the localized defect-mode will be measured using near-field scanning optical microscopy (NSOM) techniques. The structural parameters of the photonic crystals will be varied systematically in order to understand, and make controllable, the properties of the defect modes, including spatial position in the crystal, spatial size, spectral distribution, and field enhancement associated with the mode localization. In particular, we will attempt to maximize the field enhancement by combining it with the local-field enhancement at the metal surface related to resonant excitation of surface plasmons. Our ultimate objective is to use this approach to create photonic crystal structures with extremely high, localized, optical fields which may be used, e.g., in nonlinear optical applications and for single-molecule spectroscopy.