Laser interaction in sol–gel based materials—3-D lithography for photonic applications

As an example for laser interactions with polymer materials, inorganic–organic hybrid polymers were polymerized with femtosecond laser pulses, making use of two-photon absorption (TPA) processes. The material was synthesized by catalytically controlled polycondensation reactions, resulting in a storage-stable resin which is built up by inorganic (–Si–O–Si–) nm-size units which are organically functionalized with typically (oligo-)methacryl and styryl moieties, respectively. This results in materials which can be patterned by single- or two-photon absorption. The latter method allows one to directly write arbitrary structures in three dimensions into the hybrid polymer material with a resolution down to 200 nm or even below. The materials and the patterning process will be discussed with respect to applications in photonic devices