Fig. 5

Simulation of light reflectance (%) with rigorous coupled wave analysis (RCWA) on the flat surface and 3-dimensional models of nipple array (i.e., cone, pillar, and two-tier) at various incident angles. The difference in refractive index between the tunic and seawater was assumed to be 0.01. a Reflectance of 589-nm light of TE wave on the flat surface. b and c, Enlargement of the reflectance curves on the flat surface and on the nipple array arranged in grid pattern (b) and honeycomb pattern (c). Lines in b and c: thick line, flat surface; thin line, cone; broken line, pillar; gray line, two-tier. d Reflectance of 400-nm (black) and 589-nm (gray) light on the flat surface and on the pillar-model arranged in honeycomb pattern. Line in d: solid line, flat surface; broken line, pillar