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Experimental results pertaining to plasmon resonance tunneling through a highly conductive zinc oxide (ZnO) layer with subwavelength hole-arrays is investigated in the mid-infrared regime. Gallium-doped ZnO layers are pulsed-laser deposited on a silicon wafer. The ZnO has metallic optical properties with a bulk plasma frequency of 214 THz, which is equivalent to a free space wavelength of 1.4 μm. Hole arrays with different periods and hole shapes are fabricated via a standard photolithography process. Resonant mode tunneling characteristics are experimentally studied for different incident angles and compared with surface plasmon theoretical calculations and finite-difference time-domain simulations. Transmission peaks, higher than the baseline predicted by diffraction theory, are observed in each of the samples at wavelengths that correspond to the excitation of surface plasmon modes. [ABSTRACT FROM AUTHOR]

We experimentally probe the multilevel response of GeTe, Ge2Sb2Te5 (GST), and 4% tungsten-doped GST (W-GST) phase change materials (PCMs) using two wavelengths of light: 1550 nm, which is useful for telecom-applications, and near-infrared 780 nm, which is a standard wavelength for many experiments in atomic and molecular physics. We find that the materials behave differently with the excitation at the different wavelengths and identify useful applications for each material and wavelength. We discuss thickness variation in the thin films used as well and comment on the interaction of the interface between the material and the substrate with regard to the multilevel behavior. Due to the differences in penetration depths, absorption, and index contrast, different PCMs could be more suitably used depending on the application and wavelength of operation. [ABSTRACT FROM AUTHOR]

We study, by numerical simulations and experimentally, the resonant diffraction by metal (Ag) gratings in the mid-IR ( \sim 10~\mu \textm ) spectral range. The excitation of surface plasmon-polaritons facilitates narrow-band resonantly enhanced diffraction into symmetry-prohibited diffraction orders. We show that, even though the propagation losses for plasmonic modes are greatly reduced at longer wavelengths, the magnitude of the resonant diffraction peak remains limited due to diffraction into other, normally allowed, diffraction orders. The grating depth dependence of the resonant diffraction spectra indicates that with shallower gratings, the Q -factor of the resonance may become as large as 10^{3} – 10^{4}$ , while the magnitude of the peak is reduced. [ABSTRACT FROM AUTHOR]