Physical micro gratings can steer the light toward the specific direction, but they are not controllable with the fixed designing. Gratings combined with liquid crystals can realize the switchable function, moreover, small steering angle resolution can be implemented with suitable applied voltages. In this study, we will make physical gratings on ITO glass by soft embossing technique, oblique SiO2 evaporated alignment layer is then applied on top of the physical gratings. Another ITO glass with homogenous alignment layer is assembled with the one with gratings to form the active liquid crystal gratings. Due to the thick gratings(8~20um in height) on the top of the conductive ITO layer, most of voltage applied between two ITO layers drops at the grating layer, less voltage is kept at the liquid crystal layer, which results in quite high operating voltage. To reduce the operating voltage, the approach of depositing conductive layer(spin coating PEDOT or sputtering ITO) on top of the gratings surface will be also tried, the disconnection and discontinuity of the deposited conductive layer may be an issue in this case.
Fig.1 Active gratings with liquid crystal for light steering
This study mainly contains the following contents:
§ Fabricate micro gratings with soft embossing technique;
§ Deposit conductive layer on top of/beneath the micro gratings;
§ Apply different alignment layers on top of the micro gratings;
§ Assemble the active liquid crystal gratings;
§ Electro-optical characterization of different active gratings;
Successful samples will be demonstrated to the SECONDOS project.