Antireflection sub-wavelength gratings fabricated by spin-coating replication
We fabricated an antireflection subwavelength grating (SWG) on a polymethyl methacrylate (PMMA) by a spin-coating replication technique. Silicon molds of a two-dimensional tapered grating of 200nm period and 90nm deep have been obtained using electron beam lithography and reactive ion etching. Replication has been done by direct spin-coating a 9.35?m thick PMMA on the mold, followed by an appropriate mounting on a glass substrate. The transmittance in the wavelength region ranging from 500 to 800nm was measured and compared with the calculation results on the basis of rigorous coupled-wave analysis. At these wavelengths, the transmittance of the SWG was increased in comparison with that of the flat PMMA sheet, in good agreement with the theoretical calculations.
antireflection replication subwavelength gratings polymethyl methacrylate mold rigorous coupled-wave analysis nanoimprint lithography