Figure 3

Asymmetric grating. (A) Experimental and Simulated Diffraction Efficiency of the first diffracted order T1 (TM mode) at the wavelength of 520 nm. The cutoff at − 15 deg is due to the index mismatch between the sapphire substrate (n = 1.8) and the index matching oil used for that measurement (n = 1.56). See Supporting Information, for details. Both the simulation with and without a residual layer in the gap are shown. (B) SEM top view. The sample was metalized for SEM imaging. Scale bar 200 nm.