Nichtlineare Optik in Flüssigkristallen. Fortschrittsbericht

Calamitic liquid crystalline molecules may exhibit very high electronic hyperpolarizabilities what makes them attractive as NLO chromophores for second order NLO applications (χ(2)). Due to their cooperative alignment behavior liquid crystalline molecules can be very effectively oriented in external electrical fields. Compared to their non liquid crystalline analogs the macroscopic noncentrosymmetrical orientation that is necessary for χ(2)-activity can be induced much easier. In addition, chiral smectic C phases exhibit a noncentrosymmetrical point symmetry as do LC-molecules in monolayers at boundaries. In this article recent research results are reported on electric field poling of nematic phases, phasematched second harmonic generation in ferroelectric LC and the use of NLO techniques in understanding how orientational layers induce homogenous bulk alignment in LCDs.