周期性渐变折射率光学薄膜的设计及光谱特性分析

The design of periodic gradient-index optical thin film and analysis of spectral characteristics

分析折射率呈不同函数分布的周期性渐变折射率薄膜的光谱特性,分析表明光谱曲线具有负滤光片的特性。分别从最低和最高折射率、周期数、周期厚度的角度,对用共蒸法制备的周期性渐变折射率薄膜光谱特性进行了详细分析讨论。结果表明截止带中心波长和截止带宽度与周期厚度成线性关系,截止带中心波长的反射率与周期数成三次多项式关系。用堆叠和叠加两种方法设计渐变折射率多截止带负滤光片,并分析两种方法在共蒸法方式制备下的优缺点。最后总结出了渐变折射率负滤光片的设计方法。

In this paper, the analysis of the spectral characteristics of gradient-index thin film with refractive index profile of different periodic function were conducted and the result shown that their spectral characteristics curve is a notch filter. The spectral characteristics of gradient-index thin film with refractive index profile of periodic function was detailedly analyzed and discussed on the basis of co-evaporation from the point of view of the most and the least refractive index, number of periods and periodic thickness. The result shown that center wavelength in rejective band and the bandwidth has linear relationship with periodic thickness,and that the reflectance of center wavelength in rejective band has relationship of thrice polynomial of number of periods. Two approaches, stacking and superimposing, were used to design multiple-band gradient-index thin film notch filter. The shortcoming and advantage of both methods were analyzed on the basis of co-evaporation. In the end, the approach to the design of gradient-index notch filter was educed.