Investigation of the diffraction efficiencies in binary surface-relief gratings with rounded corners

The effect of corner rounding in a binary surface-relief grating on its diffraction efficiency is investigated by using a rigorous coupled-wave analysis. A super-Gaussian function is adopted to model the profiles of rectangular gratings with rounded corners. In particular, the diffraction efficiencies for transverse electric polarization are found to change significantly with the profile shapes of the reflection gratings while the transverse magnetic polarization causes clearly distinctive change in the efficiency for the transmission gratings.