Interferential lithography of Bragg gratings on hybrid organic–inorganic sol–gel materials

In this work we report on the application of laser interference lithography (LIL) to create periodic features on a photosensitive hybrid organic inorganic (HOI) sol–gel material based on 3-glycidoxypropyltrimethoxysilane (GPTMS).To better understand the mechanisms behind the grating formation and optimize the overall process, the chemical changes produced by the laser exposure have been investigated by FTIR spectroscopy. The effects of the development step on the hybrid sol–gel network have been also discussed, trying to explain the origin of the selective dissolution of the unexposed area.High quality gratings with lines down to 250 nm have been realized by LIL, in the Lloyd’s mirror configuration, and their morphological characterization has been performed by AFM and SEM.The generation of profiles with controlled sinusoidal features on HOI sol–gel materials could be exploited in different applications such as the realization of plasmonic crystals for sensing applications or as master molds for nanoimprinting lithography.