Porous anodic alumina (PAA) is a photonic crystal with a hexagonal porous structure. To learn more about the effects brought by pores on the anisotropy of the PAA, we use the orientation sensitive Mueller matrix imaging (MMI) method to study it. We fabricated the PAA samples with uniform pores and two different pore diameters. By the MMI experiments with these samples, we found that the birefringence is the major anisotropy of the PAA and that there are many small areas with different orientations that formed spontaneously in the process of production on the surface of the PAA. By the MMI experiments at different orientations of the sample with two different pore diameters, we found that the pores affect the birefringence of the sample and the effect increases with the increased inclination of the sample. To further analyze the PAA, we present a symmetrical rotation measurement method according to the Mueller matrix of the retarder. With this method, we can calculate the average refractive index (RI) of birefringence and the orientation of the optical axis of uniaxial crystal. The results also show the effect of the pores on the anisotropy of PAA.

中文翻译：

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穆勒矩阵成像法表征多孔阳极氧化铝的各向异性

多孔阳极氧化铝（PAA）是具有六边形多孔结构的光子晶体。要了解有关孔对PAA各向异性的影响的更多信息，我们使用方向敏感的Mueller矩阵成像（MMI）方法进行研究。我们制造了具有均匀孔和两个不同孔径的PAA样品。通过使用这些样品的MMI实验，我们发现双折射是PAA的主要各向异性，并且在PAA的表面生产过程中会自发形成许多具有不同方向的小区域。通过具有两个不同孔径的样品在不同方向上的MMI实验，我们发现孔会影响样品的双折射，并且随着样品倾斜度的增加，效果会增加。为了进一步分析PAA，我们根据缓速器的穆勒矩阵提出了一种对称的旋转测量方法。使用这种方法，我们可以计算出双折射的平均折射率（RI）和单轴晶体的光轴方向。结果还表明，孔对PAA的各​​向异性的影响。