Optical Characteristics Of Polarization Grating And Its Application

As a photoisomeric material,azo materials have strong polarization sensitivity.Because of its unique optical properties,it has attracted many researchers’ attention in the field of optics.Azo liquid crystal polymer is an azo macromolecule material with strong stability,so azo liquid crystal polymer material is generally used as the substrate for polarization grating.According to the polarization states of the recording light,the diffraction characteristics of the polarization gratings are different.Polarization grating has been widely used in various fields.By fusing such polarization holographic elements,more efficient systems can be designed.In the second chapter of this paper,we proposed a new naked-eye 3D scheme based on polarization grating.The optical system consists of a twisted nematic liquid crystal cell with transparent electrode layer,a quarter wave plate and a polarization grating.The electric field in the twisted nematic liquid crystal layer is controlled by controlling whether the voltage is applied on the electrode plate of the twisted nematic liquid crystal cell,so as to further control the polarization state of light passing through the liquid crystal layer.Finally,when light is incident on the polarization grating,there will be different diffraction directions according to the polarization state of incident light.This scheme utilizes the polarization selectivity of polarization grating,and can provide high quality three-dimensional visual experience to the observer on the premise of ensuring image clarity.In this paper,we built a simplified model of the system and verified its basic working principle.We also proposed the multi-point solution and discussed its feasibility in theory.In the next step,the prototype and experimental results of the system will be given.In the third chapter,we designed an all-optical logic sequence generator based on two polarization gratings recorded by orthogonal linear polarization interference and orthogonal circular polarization interference respectively.The input and output structure of the logic sequence generator is 1X4,and different output signals will be produced according to the polarization states of the incident light signal.It can produce four kinds of logic sequence signals: 1000,0100,0010 and 0001,which correspond to the input light signals of four different polarization states: P-linear,S-linear,lefthanded circular and right-handed circular.This structure provides a new idea for the research of optical communication or optical computing system.In the fourth chapter,we designed optical deflector and optical waveguide coupling input structure based on polarization grating,and proposed a new augmented reality display system.The optical system mainly includes ray deflector,coupling input grating,optical waveguide layer and coupling output grating.Compared with other AR schemes,the AR optical system not only reduces the number of micro projection light sources from two to one,but also improves the efficiency of light coupling into optical waveguide and reduces the energy loss by utilizing the singleorder diffraction characteristics of polarization grating in its coupling input structure.Light deflector realizes beam deflection based on polarization selectivity of polarization grating and rotating light characteristics of twisted nematic liquid crystal layer.The working principle of the optical system was experimentally and theoretically demonstrated to ensure its feasibility in practical application.