Light transmission properties of holey metal films in the metamaterial limit: effective medium theory and subwavelength imaging
The light transmission properties of holey metal films in the metamaterial limit, where the unit length of the periodic structures is much smaller than the operating wavelength, are analyzed theoretically utilizing the modal expansion formalism. A detailed derivation of the transmission coefficients of both one-dimensional (1D) slit and 2D hole arrays is presented. We show that under certain assumptions the transmission coefficient becomes unity independent of the parallel momentum of the incident field. This result indicates that holey metal films can be used as endoscopes; i.e. they are capable of transforming an image with subwavelength resolution from the input to the output surface of the film. We also demonstrate how such films can effectively be mapped into homogenous anisotropic films with optical properties controlled by the geometrical parameters of the holes. Lastly, the subwavelength imaging properties of an endoscope based on a 1D slit array is demonstrated for p-polarized light using numerical simulations.