Photopatterning of hybrid sol–gel glasses: generation of volume phase gratings under visible light

Free-radical photocurable hybrid sol–gel was used as a matrix precursor for the creation of crack-free holographic materials filling 100 μm thick glass cells. It combines the advantages of a glass-like material obtained under mild conditions and a spatially controlled photopatterning allowing the generation of optical elements with a few steps number. Hydrolysis and condensation reactions were first performed and investigated by 29Si NMR and FTIR spectroscopies. The presented results concern the generation of 1000 lines/mm gratings created using interference pattern at 514 nm. Diffraction efficiencies up to 90% are reached. The strategy used to avoid the cracks propagation is also described.