Interaction of light with an array of subwavelength apertures in a metallic slab

For many applications in nanophotonics, such as near field microscopy, spectroscopy, high density optical data storage, photolithography, etc, it would be very useful to find ways to have large enough optical transmission at visible wavelengths through normally-semi-opaque metallic thin films, with (and without) subwavelength apertures. Since light fields in metallic films and subwavelength cylindrical metallic apertures are mostly evanescent, optical transmission of such structures is weak. The transmission across these metallic films can be much enhanced if it is mediated by surface waves, such as surface plasmon polaritons (SPP) on the two sides of the metal film. The mechanisms of efficient light energy transfer through a two dimensional array of nano-apertures and the role of the SPPs have been under discussion for some time. At the same time, several applications of the enhanced transmission have been proposed and demonstrated. After an account of these developments, we describe results of our steady state and fsec time resolved measurements of optical properties of an array of subwavelength slits in metallic slabs, including fsec dynamics of SPPs, role of Wood anomalies in determining the transmission (T) and reflection (R) spectral features, possible use of the structure as a polarization selector and a wavelength filter in a range of visible wavelengths, reciprocity of T and R, and so on.