Study On Beam Steering In Nematic Liquid Crystals

In recent years,more and more researchers have paid attention to light field control technology.Nematic liquid crystals not only have fluidity and anisotropy of crystals,but also have good electrical and optical properties.The most prominent feature of liquid crystal devices is that they have a wide variety of structures and shapes.For example,the nematic liquid crystal can be filled into a specially designed box to achieve special functions.So far,nematic liquid crystals have become an ideal material for light field control.To some extent,the liquid crystal display is a kind of light field regulating device.The basic principle of the liquid crystal display is to control the polarization state of the incident beam by using the external electric field to regulate the arrangement of liquid crystal molecules.So far,the liquid crystal display already has a pivotal position in the display field.Based on the working principle of liquid crystal display,this paper studies the modulation technology of weak light and strong light in liquid crystal devices.The specific contents and results are as follows:Firstly,the effect of ambient temperature on the transmitted light intensity of liquid crystal display is analyzed through a simplified model.On this basis,a liquid crystal temperature control sensor and a light control liquid crystal device are designed.The variation of the phase difference of the beam after passing through the liquid crystal layer with the applied voltage is given,and the phase difference increases monotonically with the applied voltage.The relationship between the transmitted light intensity and the applied voltage is calculated,and the transmitted light intensity is periodically oscillated with the applied voltage.The variation of phase difference and output light intensity with ambient temperature in the simplified model is analyzed,and it is found that the transmitted light intensity and phase difference will change with the ambient temperature,and the change is very sensitive.Based on this principle,the possibility of using the simplified model to design the temperature sensor is put forward.It is proposed to change the moleculararrangement in the liquid crystal cell by using the side incident beam instead of the external electric field.It is found that with the increase of the power of the side-excitation incident beam,the phase of the modulated beam exit end monotonically increases,and the intensity of the emitted light fluctuates periodically.This conclusion theory can guide the experimental realization of all-optical devices with optical control.Secondly,the control technology of strong light transmission in nematic liquid crystal is analyzed.The liquid crystal molecules can be rearranged by applying an external electric field in the liquid crystal display to modulate the weak incident light.Based on this principle,the self-regulation of the beam by the thermal and molecular orientation effects induced by the strong light in the liquid crystal is analyzed.It was found that when strong light is transmitted in the nematic liquid crystal,the molecules are rearranged.This effect causes a convex lens-like property in the spatial distribution of the refractive index in the liquid crystal cell.This is the well-known self-focusing effect in the nonlinear field.Thermal effects can also occur,which is found to reduce the refractive index of ordinary light.The influence of two kinds of effect competition on beam transmission is analyzed.It is proposed that the beam transmission trajectory can be adjusted by the interaction of two Gaussian beams in nematic liquid crystal.It was found that when a suitable incident light intensity is selected,bright solitons can be observed in the nematic liquid crystal,when two Gaussian beams are at a proper distance,dipole solitons can be formed.