Polar ordering of quaslliquid crystal-An optical second harmonic generation study

lecular orientation)-defined by the direction of the align­ ing electrostatic field during preparation. This symmetry should arise from a polar alignment of the molecular dipole moments. The polar ordering of molecules can be modified by an external electrostatic field along the director, as mani­ fested by theE-field dependence ofthe SHG. In Sec. II, we present a mean-field theory for the SHG from QLC films. This is followed by a description of the experimental arrangement (Sec. III) and experimental re­ sults (Sec. IV). A discussion of our observations is given in Sec. V.