Optical Response of Nanohole Arrays Filled with Chalcogenide Low-Epsilon Media

When an array of subwavelength apertures in a metal film is filled with a chalcogenide semiconductor acting as a low-epsilon medium at optical frequencies, an increase in transmission is observed over a broad range of plasmonic frequencies, and found to be enabled by laminar flow of energy through the chalcogenide inclusions. As losses decrease in such a low-epsilon medium, with causality-bound dispersion of complex relative permittivity, a peak in transmission emerges at a wavelength tending toward that of unitary refractive index, while counterintuitively the absorption of the composite structure increases.