Spatially resolved second harmonic microscopy in novel bent shaped liquid crystalline mesogens and applications to organic QPM-waveguiding structures

Last century, one of the pioneers of liquid crystal research, Prof. D. Vorländer and his team synthesized in 1929 at the Martin Luther Universität (Halle, Germany) among hundred of new liquid crystalline compounds the first bent shaped mesogen. But further investigations of these chemical structures were not carried out at that time. It was more than 60 years later that Nori et al. at the ILCC-1996 (Brest, France) presented new advances in this field by the introduction of a novel ferroelectric bent shaped compound. Since many of the potential technological applications implemented with liquid crystalline materials are based on their ferroelectric properties, due to its faster switching response, the observation of Nori and co-workers was the starting point of a frenetically development and research of bent shaped molecules. From the fundamental point of view very interesting and peculiar features like large hyperpolarizabilities have been also observed for the first time in these bent-core achiral molecules and presently, many research-groups all around the world are involved in basic research in this growing and amazing new field.