Rolf-Peter Herr

Strongly non-linear optical ferroelectric liquid crystals for frequency doubling

Abstract From our research for novel non-linear optical (NLO) materials for frequency doublers and optical modulators we report on new ferroelectric liquid crystals, which for the first time, exhibit second order NLO coefficients (for example d 22 = 5 pm V−1, which are comparable to those of state of the art inorganic NLO materials. The novel compounds contain 5-amino-2-nitrophenyl groups attached close to the chiral centres. The switching behaviour of the new compounds, their spontaneous polarization, as well as their frequency doubling of Nd:YAG laser pulses in the S*c and in the glass state, are reported. Moreover their waveguiding properties are presented.

The synthesis of nitroaniline monomers and polymers as non-linear optical ferroelectric liquid crystals

Abstract Chiral 2-amino-4-alkoxy-5-nitrobenzoate and 5-amino-4-alkoxy-2-nitrobenzoate derivatives as well as the corresponding biphenyl derivatives were synthesized. Some of them were also derivatised to the corresponding acrylates and polyacrylates. Many of the new substances exhibit a large spontaneous polarization and large second order NLO coefficients. In addition some of them show a broad range S∗c phase. All these properties depend strongly on small changes in the molecular structures. Here we present the synthesis of these novel NLO FLC materials and discuss some of their properties.