Observation of light propagation in single layers of composite two-dimensional arrays

Composite two-dimensional (2D) polystyrene (PSt) arrays, composed of three types of PSt particles, red fluorescent, green fluorescent, and nonfluoresc ent, were prepared from an aqueous suspension These arrays form as a result of water evaporation and capillary forces. Using fluorescence microscopy a nd phase-contrast microscopy, we observed several interesting types of ligh t propagation phenomena in single layers of the array, including anisotropi c light propagation, an additive effect for light intensity, and a novel sw itch function. These characteristic light propagation phenomena indicate so me of the possibilities of the 2D array as a photonic device.