Figure 2. Structural modelling.

(a,b) Calculated unit responses of (a) a rectangular ridge with regular layers, (b) a tapered, triangular ridge with regular layers. The base width of the ridges is 500 nm. (c-e) Calculated reflection spectra of (c) a periodic array of tapered ridges, (d) a periodic array whose ridges are displaced randomly in the vertical direction between ±110 nm, and (e) a periodic array of ridges whose internal multilayers are displaced randomly in the vertical direction between ±110 nm while keeping the external shape and the layer periodicity the same. All calculations are performed under normal incident light conditions. Note that all graphs are plotted in log scale with arbitrary units. In all cases, a schematic of the corresponding structure is given.