非线性关联下液晶相控阵相位模式测量、控制与器件优化

Liquid crystal optical phased array attracted wide research interests in the field of non-mechanical beam steering and possess great application potential in future research of space optics and information optics. According to the principle of liquid crystal optical phased array, the pixel pitch of optical phased array should be comparable to the wavelength of optical wave to enlarge the beam steering angle and enhance the beam steering effficiency. Unfortunately, when the pixel pitch of the liquid crystal optical phased array is reduced to be on the magnitude of micrometers, strong nonlinear correlation effect between adjacent pixel will be found which smooth the phase profile. Under the effect of nonlinear correlation, the attempt to successfully increase spatial resolution and accurately control the phase profile will be difficult, which deteoriorates the optical performance.In this project, measurement system will be first setup to measure the nonlinear correlated phase profile of liquid crystal optical phased array. Then numerical and experimental method will be both employed to study the mechanism of nonlinear correlation and the phase profile response on the nonlinear correlation effect. Based on above mentioned results, optimization method and phase profile measurement technology will be integrated to accurately control the desired phase profile. In another aspect, we will concentrate our research on the optimization of the liquid crystal optical phased array device. In this optimization procedure, mechanism of nonlinear correlation was employed, and new large birefriegence liquid crystal would be synthethised. The final goal of this project is to minimize the influence of nonlinear correlation on the optical performance of the liquid crystal optical phased array.

液晶相控阵已被广泛应用于非机械光束偏转研究，在空间光学、信息光学等领域具有诱人的应用前景。借鉴微波相控阵理论，为实现较高的光束偏转效率和较大的光束偏转角度，液晶相控阵的像素周期应接近甚至达到光波长量级。但当液晶相控阵分辨率达微米量级后，液晶相控阵毗邻像素之间存在较强的非线性关联效应，会影响器件有效分辨率和器件相位模式的精确控制，从而恶化液晶相控阵性能。本项目拟建立非线性关联下液晶相控阵相位模式的测量装置，通过数值和实验研究，明确非线性关联机理和非线性关联下液晶相控阵相位模式的响应特性，获得精确控制液晶相控阵相位模式的优化方法；同时根据非线性关联机理对器件进行优化，研制新型大双折射率液晶，最终实现降低非线性关联效应对液晶相控阵性能影响的目的。

液晶相控阵已被广泛应用于非机械光束偏转研究，在空间光学、信息光学等领域具有诱人的应用前景。借鉴微波相控阵理论，为实现较高的光束偏转效率和较大的光束偏转角度，液晶相控阵的像素周期应接近甚至达到光波长量级。但当液晶相控阵分辨率达微米量级后，液晶相控阵毗邻像素之间存在较强的非线性关联效应，会影响器件有效分辨率和器件相位模式的精确控制，从而恶化液晶相控阵性能。因此本项目的主要研究内容包括液晶相控阵非线性关联机理与器件与优化、非线性关联下液晶相控阵相位模式的测量控制等。（1）本项目通过数值和实验研究，获得了对密集像素情形下，液晶相控阵中毗邻像素之间的非线性关联机理，明确了器件结构参数和液晶材料参数等对于非线性关联效应的影响。基于非线性关联机理的研究，我们获得了今后液晶相控阵器件优化的方向。（2）研制了双折射率大于0.42的高双折射率液晶，这种液晶材料有效降低了液晶相控阵的非线性关联作用，并有望实现~ms级的响应速度。基于该材料，项目组研制了一款新型透射式液晶相控阵器件，并在此基础上开展了液晶相控阵的近红外激光电控扫描研究。（3）获取了一套非线性关联下液晶相控阵相位模式的测量方法与装置，基于该方法，可以直接测量液晶相控阵在不同结构和材料下的相位模式，诊断出存在的物理问题，对实现高衍射效率和优化器件结构有较为重大的意义。（4）获取了一套基于相位模式测量和优化算法控制的衍射效率优化方法，这种方法无需复杂的测试系统即可将闪耀级次的光束扫描效率优化到最佳位置，是今后液晶相控阵实际工程话应用的重要保障。