We report measurements on the angular radiation pattern from an array of dye molecules embedded in a polymethylmethacrylate film deposited on a dielectric hemispherical lens. The radiation pattern is both highly structured and directed, with most of the power being radiated into the media having the higher refractive index. We also present a simulation of the far-field radiation pattern of a dipole embedded in a thin dielectric layer, which apparently has not been investigated before. The simulation matches the experimental results rather well.
We describe surface-enhanced Raman scattering measurements from a benzenethiol monolayer adsorbed on a silver-coated film that is, in turn, deposited on an artificial opal, where the latter is a close-packed three-dimensional dielectric lattice formed from polystyrene spheres. Data for a range of sphere sizes, silver film thicknesses, and laser excitation wavelengths are obtained. Enhancement factors can be in the range of 10(7). To partially explain these large enhancements, we have performed model finite-difference time domain simulations of the position-dependent electric fields generated at the opal surfaces for several experimentally studied laser wavelengths and sphere diameters.
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