Electro-optical response of reflected light from freely suspended smectic liquid-crystal films

We have studied the electro-optical response of reflected light from the surface of freely suspended liquid-crystal films (FSFs) in SmA, SmC*, and SmCA* phases. Upon application of an electric field parallel to FSFs, the film vibrational spectrum generally contains a second-harmonic component of the applied frequency. In the SmA phase, only a second-harmonic component appeared in the fast Fourier transform (FFT) spectra of the reflected light. In the SmC* phase, however, many other components also appeared in the FFT spectra of the reflected light. These complicated characteristics observed in the ferroelectric phase might be attributed to the contribution of the transient scattering mode. On the other hand, in the SmCA* phase, only the second-harmonic component appeared, similar to the case of the SmA phase. In the electric field high enough to cause an antiferroelectric-ferroelectric phase transition, however, many other components appear in the spectrum, in the same manner as that in the SmC* phase. (C) 2002 American Institute of Physics.