Pockels effect in photopolymers derived from ferroelectric liquid crystals

The Pockels effect has been studied in some photopolymers based on chiral s mectic C liquid crystals. The materials have different degrees of crosslink ing, varying from mesogenic side-chain polymers to anisotropic networks. No ne of them is switchable but there is an important electrooptic response du e to a residual molecular motion at low frequencies. In two of the studied materials, the molecular contribution disappears above several kHz and, in these cases, the electronic electrooptic effect has been fully characterize d. The electrooptic coefficients are in the range r=1 pm/V. The actual elec tronic origin of the measured effect has been confirmed by means of compari son with second-harmonic generation data. (C) 2000 American Institute of Ph ysics. [S0021-8979(00)01501-2].