In this paper, we propose to fabricate the Geometric Phase (GP) optical device in a Nematic Liquid Crystal cell (NLC cell) by using photo-alignment technique with poly [1- [4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2- ethanediyl, sodium salt] azo-polymer (PAZO) as alignment layer. During fabrication, the necessary surface alignment pattern of GP modulations for the device is firstly created and written on the PAZO films of an empty cell by using polarization holographic method. With filling E7 LC molecule, GP grating and lens are formed. The design principle, fabrication and characterization of both GP diffractive grating and lens are presented. The results show that the device can appear as a polarization-selective transmission hologram with single diffractive order, although the thickness of cell is 5 μm. In addition, the polarization state and wavefront of diffracted wave can be converted simultaneously. Thus, the device can be named as the diffractive waveplate, which provides many unique photonic applications, becoming effective way for minimizing and integrating optical devices for a photonic modular.
In this paper we demonstrate flexible polymer dispersed liquid crystal (PDLC) devices using graphene as transparent conductive electrodes on polyethylene terephthalate (PET) substrate. Graphene was grown by Low Pressure Chemical Vapor Deposition (LPCVD) technique and characterized by Raman analysis, optical and electrical measurements. Several graphene-based PDLC devices have been fabricated and their electro-optical characteristics, response time and bending ability were measured and discussed. The results support the graphene promising features for integration in flexible optoelectronics.
We study the effect of graphene oxide (GrO) on the switching voltage of polymer dispersed liquid
crystal (PDLC). The threshold voltage decreases with addition of GrO nanoparticles. Scanning
electron microscopy (SEM) supported that the size of LC droplets in GrO-doped PDLC increase in
comparison with non-doped one. PDLC:GrO layer was combined with Bi12SiO20 (BSO) inorganic
substrate into a hybrid structure and based on the surface activated photorefractive phenomena
typical for BSO, it allows the opaque-transparent states to be all optically controlled,
operating faster and requiring less intensity due to the GrO addition in PDLC.