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(a) Sketch of the device. A microscope glass slide with a thickness of 1 mm is coated with a 25-nm-thick gold film. The metallic film is perforated by a hexagonal array of holes with a grating parameter . The hole diameter is d = 405 nm. The perforated gold film is coated by a graphene sheet. (b) SEM picture of two domains (delimited by blue lines) with different orientations (white straight lines) in the holey gold film. (c) SEM top view of the final device. (d) Raman spectroscopy of the synthesized graphene layer, transferred on gold and on silicon dioxide.
Optical characteristics of the device. Absorption spectra of the uncoated holey gold film (a) and of the graphene-coated device (b) for various incidence angles.
(a) Relative absorption of the graphene-coated versus uncoated gold for various incidence angles. The black curve represents the relative absorption for a non structured metal film. For the sake of clarity, each curve is shifted vertically by 25 units with respect to the previous one. (b) Numerical simulation of the absorption of the graphene-coated device for various angles of incidence. For the sake of clarity, each curve is shifted vertically by 0.5 units with respect to the previous one.
Zeroth order transmission through graphene-coated gold (red curves) and bare gold (black curves) devices. A significant peak shift occurs when ethanol is deposited on the devices (dashed curves) by contrast with cases without ethanol (solid curves). Compared to the bare gold device, for the device coated with graphene, the wavelength-shift is enhanced by 33%. Peaks retrieve their initial positions after few minutes when ethanol is fully evaporated.
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