Polarization switching in a columnar liquid crystalline urea as studied by optical second-harmonic generation interferometry

The polar order and its switching characteristics have been investigated by means of optical second-harmonic generation interferometry in a compound N,N^′-bis(3,4,5-trialkoxylphenyl)urea (R=n-C₁₆H₃₃) being connected by intermolecular hydrogen bondings to form a columnar liquid crystalline phase. The polar structure is formed along the column by applying an electric field and is cooperatively switched by reversing the field. The polar order is relaxed to a nonpolar state within a few milliseconds by terminating the field. No macroscopic polar order exists at least in a range of a visible wavelength scale in the absence of a field.