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

The optical transmission of metal films, perforated with a periodic array of apertures, is enhanced by a resonant interaction of the incident light with surface plasmons on the metal surfaces: The maximum transmission can exceed unity when normalized to the area of the holes. Here we report a systematic study of the zero-order transmission spectra and the absolute transmission 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 proportional to the number of surface features per unit area, even for very small arrays. (C) 1999 Optical Society of America [S0740-3224(99)00108-3].