鉴于在制备过程中存在介质层厚度的随机扰动, 计算了远红外窄带滤光片厚度的鲁棒性。结果表明: 当随机度小于0.05时, 窄带滤光片全向带隙和带隙率变化不大, 但缺陷层的透射率只有原来的1/3左右; 当随机度大于0.1时, 随着厚度的随机扰动逐渐增大, 窄带滤光片的全向带隙和带隙率都逐渐减小; 当随机度达到0.2时, 窄带滤光片的第一个全向带隙消失, 第二个全向带隙向短波方向偏移明显, 缺陷层的透射率也只有原来的1/3左右; 当随机度达到0.5时, 窄带滤光片的两个全向带隙全部消失。制备了一种远红外窄带滤光片, 其结果较好地验证了厚度的随机扰动对滤光片的影响。

Due to the random fluctuation of thickness of layers in the deposition process, the robustness of thickness of narrowband filters for far infrared is calculated. The results show that the omnidirectional band gap and the gap ratio of the narrowband filter change little in accordance with the value of random degree less than 0.05. However, the transmission ratio can only reach to about 1/3 of the original one in the defect layer. Both the omnidirectional band gap and the gap ratio of the narrowband filter decrease with the increase of random fluctuation of thickness when the random degree is over 0.1. The first omnidirectional band gap disappears while the second one obviously transfers to the shortwave direction when the value of random degree reaches to 0.2. Meanwhile, the transmission ratio also reaches to about 1/3 of the original one in the defect layer.The two omnidirectional band gaps disappear totally when the value of random degree reaches to 0.5. A kind of narrowband filter for far infrared is prepared, and the results preferably demonstrate the effect of random fluctuation of thickness on the narrowband filter.