Large second-order optical nonlinearity in a molecular crystal formed from a chiral smectic liquid crystal

A new approach to achieving a large second-order nonlinear optical susceptibility in a chiral liquid crystal is described. This approach uses an aligned smectic-C* liquid crystal as a template for forming a molecular crystal, which freezes out the rotation of the molecular dipoles and thereby greatly enhances the noncentrosymmetric order of the structure. Analysis of the measured second harmonic generation gives maximum values of individual susceptibility components of ∼25 pm/V, which are stable when the field is removed.