Research for Free-Space Optical Beam Control with Liquid Crystal

在光互连和光计算领域，液晶被认为是简单而高效的器件。在本研究中，我们实时地研究了液晶自由空间光束控制装置的设计和制作。平成7学年以来近两年来的主要研究成果如下：1)阵列型液晶光束器件的研制与特性估算：我们研制了一种均匀向列型液晶平板，采用分布电阻率电极，可用线性或二次函数连续调制波前。实验结果与理论计算结果吻合较好。在此基础上，设计并制作了空间位相调制器单元单元和具有分布电阻电极的单元阵列。2)高效的液晶光束器件阵列光源：基于Talbot EF…更有效的是，我们设计并制作了一种新型的由大子孔径多能级位相光栅晶束器件组成的阵列照明器，得到了位相光栅的细节，提高了光学吞吐量。3)二维照明器的设计和制作：对二维照明器的扩展很简单。通过在一块平板上实现由两个一维Talbot平板的相位和组成的二维相位分布，我们可以得到各种SLM器件孔径比的强度方向图。4)波导阵列照明器的理论和实验评估：我们成功地在实验中证实了高对比度强度分布的存在，直到波导边缘。5)二维液晶光束器件的研究：我们得到了新型二维液晶器件的概念，可以实现低功率、高速度的高效波前调制。较少

The liquid crystal is considered as simple and efficient devices in the field of optical interconnects and optical computing. In the present research, we investigated the design and fabrication for free-space optical beam control device with liquid crystal in realtime. The main results throughout these two years' research since the Heisei 7th academic year, are presented below.1) Fabrication and characteristic estimation of array type liquid crystal optical beam device :We developed a homogeneous nematic liquid crystal panel using electrodes with distributed resistivity for the purpose of continuously modulating the wavefront either by a linear or quadratic function. The experimetal results show excellent congruity with the theoretical calculations. Furthemore, we designed and fabricated both spatial phase modulator unit cell and cell array incorporating electrodes with distributed resistivity.2) Efficient array illuminator for liquid crystal optical beam device :Based on the Talbot ef … More fect, we designed and fabricated a new type of array illuminators consisting of a multilevel phase grating crystal beam device with large subapertures, Details of the phase grating and the improved optical throughput are obtained.3) Desin and fabrication of two-dimentional illuminator :The extension to a two-dimensional illuminator is straightforward. By implementing on one plate a two-dimensional phase profile which consists of the phase sum of two one-dimensional Talbot plates but superimposed orthogonally, we can obtain intensity patterns for various SLM devices aperture ratios.4) Theoretical and experimental evaluation of waveguide array illuminators :We successfully confimed the theoretical results in an experiment demonstrating the existence of the high-contrast intensity distributions up to the edge of the waveguide. We concluded that waveguide array illuminators are expected to be useful for optical interconnects.5) Examination of two-dimentional liquid crystal optical beam devices :We obtained the concept of novel two-dimentional liquid crystal devices for efficient wavefront modulation with low electric power and high speed. Less