Measured transmission data (logarithmic scale) of the diffraction orders at λ = 1,565 nm. (a) Single-layer grating and (b) double-layer grating. The numbers next to the transmission peaks indicate the diffraction order. The inset in both plots shows the data on a linear scale.
Lai et al. Nanoscale Research Letters 2012 7:645 doi:10.1186/1556-276X-7-645