POLARIZATION PROPERTIES OF AN AMPLITUDE NEMATIC LIQUID-CRYSTAL GRATING

A nematic liquid crystal (LC) grating is prepared using an amplitude-t ype grating electrode structure and a homogeneous initial alignment pa rallel to the grating electrode direction. The polarization properties of the LC grating are investigated by measuring Stokes parameters of diffracted light under differently polarized incident light. The elect rically variable polarization modulations of diffracted light are veri fied for the first time, as well as the diffraction light intensity mo dulations. Moreover, the LC grating exhibits some unique optical prope rties, such as symmetric diffraction light intensities but antisymmetr ic polarization states in corresponding positive and negative diffract ion orders when the incident light is linearly polarized parallel or p erpendicular to the grating direction. A polarization grating model is proposed to clarify the unusual polarization properties, which sugges ts that it may be related to the antisymmetric LC molecular orientatio n domains induced by the grating electrode structure. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)01211-2].