基于亚波长二维光栅的入射角不敏感颜色滤光片研究

摘要

提出了一种基于二维亚波长光栅的具有非偏振光入射下入射角不敏感特性的反射式颜色滤光片。采用严格耦合波分析方法详细分析了光栅周期、光栅层厚度以及固定光栅占空比下光栅的结构尺寸对反射率峰值、反射带位置及带宽的影响。结合入射角不敏感特性,经过优化设计得到了光栅的最终结构参数,获得了中心波长424 nm,峰值反射率56%,带宽45 nm的反射滤光片。模拟结果表明,在非偏振光入射下,此滤光片的反射光谱表现出显著的入射角不敏感特性。当入射角高达60◦时反射带的中心波长偏移6 nm反射率下降6%带宽增加8 nm其参数没有较大变化通过调整光栅的结构参数可在400—520 nm范围内调节滤光片的中心波长以获得不同颜色的入射角不敏感滤光片。%A novel design of reflective color filters based on a two-dimensional subwavelength grating structure is proposed, which exhibits an incident angle independent property with unpolarized incident light in the visible range. By using rigorous coupled-wave analysis method, the effects of the grating period, the groove depth and the size of the structure on the reflectance spectrum are investigated in detail. The structural parameters of the gratings are optimized, and a color filter with high angular tolerance is achieved. Simulation result shows that the maximal reflectance is 56% at 424 nm with a bandwidth of 45 nm, and that the grating can almost keep its reflectance, bandwidth and the peak position at the incident angle up to about 60◦under unpolarized incident light. The peak position of the color filter can be tuned from 400 nm to 520 nm by changing structural parameters of the gratings, and keep its incident angle-independent property.