Phase Modulation Device Model Based On The Pixel Unit Of Micro-nano Liquid Crystal

With the rapid development of the optoelectronic field,three-dimensional display ushers in the spring.The classical holography can only achieve the static three-dimensional display,and the holographic video display technology based on the principle of wave optical diffraction is recognized ultimate goal of the dynamic three-dimensional display.Holographic video display requires huge space-bandwidth product and angle of wide viewing field,it is a good choice to design active wavefront modulation devices with micro-nano scale pixel units,however,if we use the existing spatial light modulator(SLM),such as Liquid Crystal on Silicon(LCOS),to reduce the pixel size,we will face physical and technology problems such as the fringe effect,low diffraction efficiency,and less 2? phase modulation.Metamaterials with different electromagnetic properties and liquid crystals with good optical nonlinearity and birefringence have become the hot areas of research.It is hopeful for holographic video displays to break the bottleneck by combining active liquid crystal and surface plasmon(SP)of sub-wavelength deep metal gratings.In this paper,aiming at the limitation of the spatial bandwidth product in the exiting SLM devices,a novel phase-modulated device model that meets the requirement of holographic video display is designed which based on the SP and the electronically tunable micro-nano pixel cell array of the liquid crystal.The results of the experiment confirmed that the model can modulate light at the sub-wavelength scale and reach the phase modulation range of 2?.The paper include the following two aspects of the research and results:1)The Fabry-Perot(F-P)resonant cavity and SP are further studied on the basis of the grating resonance phenomenon of metal-dielectric-metal(MDM)structure.The results show that the phase of reflected light is closely related to F-P resonance in sub-wavelength deep metal grating phase modulators,and the key to achieve phase modulation is the design of device architecture.In this paper,an active phase modulation device model is designed,which replaces the traditional LCOS top electrode layer with sub-wavelength deep gold metal gratings,and uses the SP in the grating silts to modulate the phase of the reflected light.In the display unit of thelum and without increasing the thickness of the medium layer,experimental results show that by optimizing the sub-wavelength deep gold metal grating period,height and silt width,compared with the existing grating modulation device,the proposed device model has better robustness,less oxidation and can still achieve the phase modulation amount.It is convenience for subsequent processing.2)The driving voltage and photoelectric effect of the liquid crystal display device have a direct effect on the performance of the display.In this paper,we calculated the threshold voltage of the proposed device model and studied the deflection of the liquid crystal director at different voltages.By researching the pixel pitch of the device model,different voltages applied to the adjacent pixels and pretilt angle of liquid crystal director,we find a way to reduce the fringe field and suppress the reversal of liquid crystal pretilt angle.Finally,we obtained the best data parameters,when the non-target pixels is applied with an initial voltage of 1V which below the threshold voltage and the liquid crystal pretilt angle is 2°,the performance of the phase modulation device is optimized.