Determining the refractive index dispersion and thickness of hot-pressed chalcogenide thin films from an improved Swanepoel method
Determining the refractive index dispersion and thickness of hot-pressed chalcogenide thin films from an improved Swanepoel method
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DOI：
10.1007/s11082-017-1057-9
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发表时间：
2017-06
影响因子：
3
通讯作者：
Y. Fang;D. Jayasuriya;D. Furniss;Z. Tang;Ł. Sójka;C. Markos;S. Sujecki;A. Seddon;T. Benson
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文献类型：
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作者：
Y. Fang;D. Jayasuriya;D. Furniss;Z. Tang;Ł. Sójka;C. Markos;S. Sujecki;A. Seddon;T. Benson
由Swanepoel提出的众所周知的方法可用于仅从透射干涉条纹的最大值和最小值处的波长值确定近红外区域中的薄膜的折射率色散。为了将该方法扩展到中红外光谱区域（我们的测量范围为2至25 µm），通过使用两项Sellmeier模型代替Cauchy模型作为色散方程来改进该方法。标称批次组成为As40Se60（at.%）的硫属化物薄膜和Ge 16 As 24 Se 15.5 Te 44.5（at.%）通过热压技术制备。用改进的方法测定了硫系薄膜的折射率色散，标准偏差小于0.0027。通过与棱镜测量同一批次Ge 16 As 24 Se 15.5 Te 44.5材料的基准折射率值进行比较，该方法的准确度在3.1 µm波长处优于0.4%。
The well-known method presented by Swanepoel can be used to determine the refractive index dispersion of thin films in the near-infrared region from wavelength values at maxima and minima, only, of the transmission interference fringes. In order to extend this method into the mid-infrared spectral region (our measurements are over the wavelength range from 2 to 25 µm), the method is improved by using a two-term Sellmeier model instead of the Cauchy model as the dispersive equation. Chalcogenide thin films of nominal batch composition As40Se60(at.%) and Ge16As24Se15.5Te44.5(at.%) are prepared by a hot-pressing technique. The refractive index dispersion of the chalcogenide thin films is determined by the improved method with a standard deviation of less than 0.0027. The accuracy of the method is shown to be better than 0.4% at a wavelength of 3.1 µm by comparison with a benchmark refractive index value obtained from prism measurements on Ge16As24Se15.5Te44.5material taken from the same batch.