  Investigations of the optical response of subwavelength structure arrays
milled into thin metal films has revealed surprising phenomena including
reports of unexpectedly high transmission of light. Many studies have
interpreted the optical coupling to the surface in terms of the resonant
excitation of surface plasmon polaritons (SPPs), but other approaches involving
composite diffraction of surface evanescent waves (CDEW) have also been
proposed. We present here a series of measurements on very simple
one-dimensional (1-D) subwavelength structures with the aim of testing key
properties of the surface waves and comparing them to the CDEW and SPP models.
