Simultaneous observation of light localization and confinement in near-field optics

We report on the observation, in direct space, of both light localization a nd confinement effects near lithographically designed structures. The sampl e is observed in the optical near-field zone with a Photon Scanning Tunneli ng Microscope (PSTM). Several patterns composed of a few periods of TiO2 do ts, arranged as a hexagonal lattice, have been investigated. When the centr al dot of the pattern is removed, a phenomenon of light localization above the vacancy can be observed in the PSTM image. The occurrence of this pheno menon can be related to the variation of the electromagnetic local density of state.