The Design Of The Beam Control Device Based On The Principle Of Liquid Crystal Display

Liquid crystal has the fluidity of liquid and anisotropy of crystal,in addition,it also has good electro-optical properties.Because of its fluidity,its morphological plasticity is fine,so it can make a variety of shapes of the box filled with liquid crystal to make a variety of electro-optical devices.Among them,the most mature device is liquid crystal display,which has set off the scientific and technological revolution in the display field,so that lightweight,low-power liquid crystal display devices are widely used in the optoelectronic field.Liquid crystal display skillfully introduces polarizer and applied voltage to control device on each pixel transmittance.Inspired by this principle,this paper uses oblique incident parallel light instead of applied voltage to reorient liquid crystal molecules to control the light intensity of vertical incident signal beam.So far,the liquid crystal materials used in the manufacture of optoelectronic devices are thermotropic liquid crystals,whose electrical and optical properties are affected by the ambient temperature.In this paper,the influence of ambient temperature on light intensity modulation will be analyzed.In addition,due to the huge nonlinear coefficient,the self-focusing effect will be induced when the Gaussian beam enters the liquid crystal.When the self-focusing effect induced by the beam is balanced by its own diffraction broadening,the self-trapping beam,called spatial soliton,will be formed.In this paper,we will try to use soliton beam to reorientate the liquid crystal molecules to modulate the light intensity of vertical incident signal beam.This paper mainly designs the beam control device based on the principle of liquid crystal display,and the main contents are as follows:Firstly,the molecular orientation effect in nematic liquid crystal is analyzed when applied electric field or light field.On this basis,a light intensity control device is designed,based on the principle of liquid crystal display.The transmission theory of vertical incident signal beam in this model is analyzed by using the theory of crystal optics and Jones matrix.It is found that the signal beam is decomposed into ordinary light and extraordinary light whose vibration directions are perpendicular to each other after entering the liquid crystal layer.The applied electric field or light field changes the orientation angle of the liquid crystal molecules,thus changing the refractive index of extraordinary light.Therefore,the polarization state of the signal beam can be changed by applying electric field or light field.Secondly,in 5CB liquid crystal cell,the oblique incident control beam is introduced instead of the applied voltage to modulate the arrangement of liquid crystal molecules in this cell.It is found that the oblique incident control beam can replace the electric field to reorient the liquid crystal molecules,thus modulating the transmission intensity of the signal beam.The temperature characteristics of 5CB liquid crystal is also used to analyze the effect of ambient temperature on light-light modulation.The theoretical analysis shows that the phase difference of the output beam increases monotonically with the increase of the intensity of the control beam,and the intensity of the output beam changes periodically with the increase of the intensity of the control beam.When the intensity of control beam varies from 0.5MW/m~2to 1.1 MW/m~2,the intensity of the output signal beam can be linearly modulated.When the intensity of the control beam is fixed,the intensity of the output beam changes periodically with the temperature rising.This discovery provides a feasible scheme for the realization of light-light modulation.Finally,the soliton beam incident perpendicular to the center of the liquid crystal layer is introduced instead of the applied electric field to control the orientation angle of the liquid crystal molecules.It is found that the liquid crystal molecules will be reoriented when the soliton beam propagates in the liquid crystal,and the reorientation angle of the liquid crystal molecules is large in the region with strong light.The output intensity of the signal beam can be controlled by changing the peak power or the width of the soliton beam.In addition,we design the GUI interface of beam modulation in nematic liquid crystal by using MATLAB software,which provides a feasible way to realize the modulation of signal light intensity.