Fabrication of arrays of sub-wavelength nano-apertures in an optically thick gold layer on glass slides for optical studies

We report on the fabrication of two-dimensional arrays of nano-optical apertures in gold layers by electron beam lithography (EBL) on a transparent glass substrate. 30 x 30 μ m(2) large arrays of high aspect ratio sub-wavelength cylinders (400 nm diameter with period of 1.81 μ m) and annular apertures (diameters 250/330 nm and 3 10/330 nm inner/outer with period of 600 nm) were patterned in a 750 nm thick resist layer using a high contrast negative tone resist. The resist structures show sharp and vertical edges after development. The 150 nm thick deposited gold layer ensures optical transmission of less than 1.1 X 10(-4) at 633 nm wavelength. White light based optical characterizations agreed with theory predictions and prove the good quality of the structures.