抄録
We have performed the electro-optical measurements in an antiferroelectric liquid crystal MHPOCBC. A Landau-type theory was developed to analyze frequency dispersions in the second-order response and we observed the soft mode in the chiral SmC_α phase. This is a direct consequence that the SmC_α phase is induced by the condensation of a tilting mode. We have adopted another measurement geometry to more clearly observe the soft mode.