Characterization of holographic polymer dispersed liquid crystal transmission gratings

We investigate physical properties of polymer dispersed liquid crystal tran smission gratings which influence the light diffraction efficiency behavior . Scanning electron microscopy is used to determine the orientation and sha pe of nanometer-sized liquid crystal droplets in a polymer host. Dependence of diffraction efficiency on light polarization suggests that the orientat ion of a liquid crystal within the ellipsoidal droplets is axial. The distr ibution of droplet orientations appears to vary for different grating spaci ngs. The switching properties of the gratings are investigated and analyzed with a sinusoidal dielectric tensor modulation model. The analysis also ta kes into account orientational distribution of average directors and spatia l distribution of the droplets. Temperature dependence of diffraction effic iency is tentatively explained by a structural transition within the drople ts and the presence of impurities in droplets. (C) 2001 American Institute of Physics.