氟化钇薄膜的低温红外光学性能

Infrared Optical Properties of YF3 Films at Low Temperature

采用离子束辅助电子束蒸发方法在硒化锌基底上制备氟化钇(YF3)单层650 nm薄膜样品,基于其空间低温应用环境,利用液氮杜瓦及傅里叶变换红外光谱仪建立的薄膜材料变温光学测试系统,测试了薄膜样品在80~300 K温度条件下,在1~15μm波长范围的光谱透射率。基于该测试结果,利用全光谱反演拟合方法对YF3薄膜在低温下的折射率变化情况进行了研究。结果表明,YF3薄膜折射率均随波长增大而减小,且在不同温度下变化趋势基本相同。基于Cauchy色散公式得到了YF3薄膜在低温下的折射率与波长及温度的关系表达式,其折射率温度系数dn/dT约为6.95×10−4K−1,对在任一低温下YF3薄膜折射率快速计算提供了一个较好的方法。最后通过比较该公式得到的在300 K与80 K温度下的设计值与实际测量值的结果验证了该折射率计算表达式的准确性。

Yttrium fluoride(YF3)film with physical thickness of 650 nm was deposited on ZnSe substrates by an electron beam evaporation system.Based on its space low temperature application environment,the transmittance of YF3 film in the range of 1 to 15μm was measured by a Perkin Elmer FTIR cryogenic testing system from 80 to 300 K with a step length of 50 K.Then,the relationship between the refractive index and wavelength at different temperatures was obtained by the full spectrum inversion fitting method.Results show that the refractive index decreases with the increase of wavelength,and the variation trend is basically same at different temperatures.Based on the Cauchy formula,the relationship between the refractive index of YF3 film and the temperature or wavelength can be obtained by fitting method,the coefficient of refractive index depends on temperature is 6.95×10−4 K−1.Finally,the accuracy of the formula is verified by comparing theoretical value obtained by the formula with the measured results at 80 and 300 K.