  We compare the characteristics of two types of patterns obtained with two
azopolymer materials: a Gaussian random pattern and a quasi-random grating
pattern. The surface structurations have been obtained with a simple bottom-up
technique by illuminating azopolymer thin films with a single laser beam. We
demonstrate the interesting generated properties of these two surfaces. In
particular, the surface with quasi-random gratings can address beam splittings
for light coupling in different directions in an ultra-thin film. We use these
two surfaces as a mold and replicate them on a transparent elastomeric material
and we demonstrate a very good light entrapment. We also show that the
efficiency of light trapping is 20% better with the quasi-random gratings than
with the Gaussian random surface, and is close to 40%.
