Second order nonlinear optical response of nematic liquid crystalline main chain polymers

We have synthesised and carried out preliminary characterisation of NLO-active semiflexible main chain polymers with a head-to-tail structure which exhibit a nematic liquid crystalline mesophase. We predict that the nematic order facilitates a large number of dipoles to couple collectively to a dc poling field. From this process we expect an enhanced χ(2) response. We attribute a slow response to a poling field and subsequent relaxation to hairpin diffusion along the polymer chains. Values of r33-r13 of 50 pm/V were observed.