The research group led by Roberto Osellame has developed an innovative technique of 3D laser lithography for the nano-structuring of crystalline materials. This process, based on the use of ultrashort pulsed lasers to locally modify the response of the materials to chemical etching, allows to create three-dimensional nano-optical devices directly inside dielectric crystals like YAG and sapphire, which play a key role in many photonic applications.
This discovery is very important from the technological point of view, because to date, through conventional techniques of micro- and nano-processing of materials, it is only possible to modify these crystals on their surface, thus obtaining purely two-dimensional structures. With the new method, on the other hand, it has been possible to fabricate devices such as photonic crystal waveguides and diffraction gratings, buried within the volume of the crystals. These results, published in the February issue of the journal Nature Photonics, open the way to the development of a new generation of photonic devices.