Surface relief structures for light coupling at air/liquid interface

Relief patterns were photoinduced on the surface of a thin film floating on water. The structures have a length of several millimeters with a width of 33 μm. Both the intensity and the polarization of the irradiated light change the characteristics of the generated patterns. The light induced structuration is the result of simultaneously a reversible material transport originated by photoisomerization of azobenzene units and a process of self-organization of the molecules. The structures were used as waveguide or grating to couple light at the air/liquid interface on a short or long distance. The fabrication of waveguides can be extended to any liquid substrates.