LARGE AND STABLE 2ND-HARMONIC GENERATION IN A CRYSTALLINE PHASE OF A FERROELECTRIC LIQUID-CRYSTAL

Second harmonic generation (SHG) has been studied in a nitro-substituted ferroelectric liquid crystal cooled from the smectic-C* into a three-dimensional crystalline (K) phase in an applied electric field. The SHG efficiency in the K phase is found to be deff≳4.5 pm/V, about 25 times the value in the SmC* phase, and, unlike the SmC* case, remains constant in zero field for ≳25 h. A quantitative analysis of the polarization dependence of the SHG reveals that the dominant d coefficients contributing to the measured signal differ for the two phases, and that the orientation of the liquid-crystal director in the K phase is modulated in one dimension.© 1995 American Institute of Physics.