GSP 插入LCOS 的可行性探讨

硅基液晶(LCOS)是最适合用于全息视频显示的空间光调制器之一,但是受限于小衍射角和低分辨率的特性,当前市场上的LCOS并不完全适用。近年来出现的超常表面(例如,间隙表面等离子体激元)具有独特的特性,提供了一种新的对光传播进行控制的方法。文中采用数值方法研究了在LCOS中插入超常表面结构,旨在解决小衍射角和低分辨率的问题。为了实用化,使用铝作为金属层、三氧化二铝层作为电介质层,生成GSP结构。首先,研究了铝在可见光频率的光学特性以及相应的法布里珀罗共振子模型。然后将初始GSP结构插入到LCOS中,得到液晶中的电场分布,进一步观察液晶中指向矢分布的变化。数值模拟的结果表明,所提出的结构对远场衍射光具有一定的影响,并且全息显示的视场角也发生一些改变。因此,这里提出的在LCOS装置中插入GSP的方案在技术上是可行的。

Discussion on feasibility of inserting the GSP into LCOS

The liquid crystal on silicon(LCOS) is one of the most appropriate spatial light modulators for holographic video display but the off-the-shelf LCOS is not suited because of mainly its small diffraction angle and low resolution. Metasurface, for example, gap-surface plasmon (GSP), has recently emerged as an innovative approach to control light propagation with unprecedented capabilities. In this paper, the feasibility of inserting one kind of metasurface into the LCOS was numerically discussed to deal with the problem. To the practical purpose, aluminum was used as the metal layer, the aluminum oxide layer was used as the insulating layer to form GSP structure. Firstly, the optical properties of aluminum at visible frequencies and the relative Fabry-Perot resonator model were studied. The preliminary structure then was inserted into LCOS to observe its effects on the electric field in the liquid crystal and consequently the changes of the liquid crystal director. The numerical simulations results show that the proposed structure has some influence on the diffraction of the far-field light and there are some changes in the viewing angle of the holographic display. The purpose of inserting the GSP into LCOS devices proposed here is technically feasible.