| dc.description.abstract | In this thesis, we discuss the optoelectronic properties of axially symmetric twisted nematic liquid crystal (ASTNLC) devices fabricated by mechanical rubbing process and photo-alignment method under the conditions of electrically controlled polarization rotator with high output linear polarization rotation characteristics based on twisted nematic liquid crystal (TNLC) cells.
In the first part, the ASTNLC fabricated through the mechanical rubbing process is examined first. This ASTNLC device is made of two substrates, treated with poly(9-vinylcarbazole) (PVK) and polyimide (PI) as the two alignment films. By measuring the light intensity distribution of linearly polarized light and azimuthal symmetrically polarized light fields after passing through the ASTNLC device, the polarization elliptical orientation angle distribution and degree of linear polarization distribution of the light field are obtained through Stokes calculation to understand the effect of the ASTNLC device on the light field. Theoretically, the device performance is calculated through simulation using the actual device parameters obtained during the manufacturing process combined with the physical parameters of the liquid crystal, and then compared with the actual results. Finally, the errors, resulting from the device using this manufacturing process, are analyzed.
The second part is to test the ASTNLC made of photo-alignment technique. This ASTNLC element uses azo dyes methyl red (MR) and brilliant yellow (BY) as the photoalignment materials with suitable surface anchoring. For the BY film plated on a substrate and the MR doped in the liquid crystal, light sources of different wavelengths modulated by the polarization conversion element are used for two-step photo-alignment. BY will form a concentrically circular alignment on the surface of the substrate, and MR will adsorb on the surface of the other substrate to form a radial alignment, thereby forming an ASTNLC element. By measuring the light intensity distribution of linearly polarized light and azimuthally polarized light fields incident on the device, the polarization elliptical orientation angle distribution and the degree of linear polarization distribution of the light field are obtained by using Stokes calculations to understand the impact of the device on the light field. Then, the simulation results of different liquid crystal layer thicknesses are used to analyze the actual situation of the device. Finally, the errors, resulting from the device fabricated using this method, are also analyzed. | en_US |