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Quasi-phasematched (QPM) Second Harmonic Generation (SHG) in poled polymer waveguides has been realised.Rib-waveguide devices were fabricated by lithographic techniques like multilayer spin coating and reactive ion etching, well known from semiconductor technology. Guest-host-systems [Cyanobiphenyl-Polymethylmethacrylat (CN-PMMA)] as wellas co-polymers have been used as the NLO-waveguiding layer between Perfluorcyclobutane (PFCB) layers acting as lower refractive index claddings. Cut-off experiments yield waveguide losses of 3 dB/cm and endfire coupling losses of 3-5 dB. The QPM-period has been determined experimentally to A 20 tm for a 4 tm wide Rib-waveguide by recording Maker fringes. Periodically poled waveguides were realised using Corona poling in combination with corrugated surfaces. The period A of the poling structure was varied continuously between 15 tm and 30 Itm using a fan-shaped corrugation structure. SHG tuning curves exhibit a relative acceptance bandwidth of 3.7 .lO which indicates an effective interaction length 1eff over the full waveguide length of 4 mm.

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Several homologues of new liquid crystals of nonchiral, banana shaped molecules are investigated by generation of the second harmonic (SHG) of an optical wave. Symmetry properties of the apparent thermodynamic phases are studied and first quantitative values of the nonlinear optical coefficients are given.