基于聚合物网络液晶的近红外波段快响应相位调制器

Fast Response Phase Modulator in Infrared Waveband Based on Polymer Network Liquid Crystal

相位型液晶空间光调制技术已经广泛应用于自适应光学、信息光学等领域,然而一直存在着响应速度较低的问题。为了提高相位型液晶空间光调制器的响应速度,采用聚合物网络液晶制备近红外波段亚毫秒响应相位调制器,并对其光散射特性和瞬态响应特性进行了研究。通过降低聚合反应温度并提高紫外(UV)固化照度,可以降低器件的光散射强度,实现较好的相位调制。在此基础上,初步研究了聚合物网络形貌对最大光散射强度的影响。在高电压加载下,聚合物网络的电致伸缩效应会极大降低聚合物网络液晶的响应速度,使其达到秒级,经分析认为通过采用高介电各向异性的液晶材料可以降低阈值电压,提高器件的响应速度。

The slow response has limited further application of phase only liquid crystal spatial light modulator in many research fields, such as adaptive optics and information optics. Polymer network liquid crystal （PNLC） is proposed to apply in phase only liquid crystal spatial light modulator to enhance the response speed to sub-millisecond time scale. The light scattering and transient response on applied voltage are elucidated. The light scattering of PNLC is minimized by lowering the curing temperature and increasing the curing intensity. The morphology of polymer network is also taken by scanning electron microscope （SEM） to elucidate the mechanism of light scattering in polymer network liquid crystal. Upon loading large voltage to generate large phase retardation, electrostriction effect is found to slower the response time to the order of second scale. Lower threshold voltage is proposed to minimize the influence of electrostriction by employing large dielectric anisotropy liquid crystal solvent.