Propagation characteristics of a random-metal dielectric film for an optical near-field generator

The propagation characteristics of a random-metal dielectric film acting as a propagating far-field light/optical near-field converter were investigated. A finite-difference time-domain method was used for the analysis of the characteristics, because of the complicated structure of the film formed with fused silica balls and silver paste. The propagating efficiency of the optical intensity was estimated, and two efficiency-determining factors were clarified; the optical coupling efficiency determined by the silica ball size, and the absorption determined by the silver layer between the silica balls.