3D sol–gel printing and sol–gel bonding for fabrication of macro- and micro/nano-structured photonic devices

Photonic integrated circuits (PIC) can be mass-produced by 3D-printing technologies in combination with advanced hybrid inorganic–organic materials. In this work we present the development of hybrid inorganic–organic materials based on the fast sol–gel process (FSG) which can be used as a “tool kit” for the fabrication of advanced optical materials. We present routes to fabrication of FSG materials with a variety of properties: the materials may exhibit mechanical toughness or be elastic; they may be thermally and UV-curable, they can have a tailored refractive index value and tailored chemical environment, such as an aromatic matrix. Using these materials, we demonstrated strong optical bonding between optical components for solar energy and optical fiber coupler systems. We demonstrated fabrication of macroscale optical elements by 3D-printing methods, such as soft lithography, inkjet, and digital light processing (DLP) printing. We also demonstrated 3D-printing fabrication of nano/microscale optical elements by soft lithography, nanoimprint lithography (NIL), and direct laser writing (DLW). The obtained 3D-printed sol–gel optical elements were found to exhibit mechanical advantages: improved surface quality, resistance to solvents, improved adhesion to glass substrate and stability to temperature above 200 °C compared with 3D-printed organic polymer elements. In addition, the sol–gel elements present the following optical advantages: improved optical quality, improved optical transmission, and durability to laser radiation. We believe that this class of materials is a promising candidate for use in mass production of photonic integrated circuits (PIC) by 3D-printing technologies.