Surface-plasmon-enhanced transmission through hole arrays in Cr films

The optical transmission of metal films, perforated with a periodic array o f apertures, is enhanced by a resonant interaction of the incident light wi th surface plasmons on the metal surfaces: The maximum transmission can exc eed unity when normalized to the area of the holes. Here we report a system atic study of the zero-order transmission spectra and the absolute transmis sion efficiency as a function of the geometry of hole arrays fabricated in chromium films. The energy-integrated transmission, normalized to the area of the holes, is independent of the hole diameter, but is found to be propo rtional to the number of surface features per unit area, even for very smal l arrays. (C) 1999 Optical Society of America [S0740-3224(99)00108-3].