Surface patterning for light extraction in luminescent sol-gel films

We report here a method to enhance light extraction from the top face of a TiO 2 waveguide doped with a molecular emitter. Sol-gel TiO 2 surface is patterned by a 2D photonic crystal with a 400-nm period and a 40-nm depth, as verified by Scanning Electron Microscopy and Atomic Force Microscopy. We evidence that light emitted in the TiO 2 layer is efficiently extracted by the surface patterning and quantify the extraction enhancement by measuring the emission spectra as a function of the emission angle. We measured an enhancement factor of 3 within 50° off normal.