Multi-photon polymerization of inorganic-organic hybrid polymers using visible or IR ultrafast laser pulses for optical or optoelectronic devices

Integrated passive and active devices are the key components in current and future information technology. In order to fulfill requirements in miniaturization for (integrated) optical or electronic devices, nano-scaled materials with a good compatibility to high-resolution processing techniques are needed. According to these requirements, multi-photon techniques attract much attention by providing a resolution far beyond the diffraction limit. The patterning of the inorganic-organic hybrid polymers, which are synthesized by catalytically controlled hydrolysis/polycondensation reactions, will be discussed with respect to the underlying photochemical processes. Emphasis will be on the direct writing of structures using femtosecond laser pulses, making use of two-and three-photon absorption (TPA/3PA) processes with visible or IR light, which also allows one to write arbitrary 3D structures. Due to the very sharp threshold fluence for these processes and its non-linear behavior, features down to 100 nm can be realized by choosing a suitable combination of material formulation and patterning parameters. Voxel arrays were written, whereas the resulting voxel sizes are compared to a growth model, and the influence of radical diffusion and chain propagation is discussed. In order to determine the TPA cross-section and to estimate the role of the photoinitiator, a z-scan experiment was realized. The initiators' cross-sections will be correlated to the resulting voxel sizes.