Sellmeier coefficients and dispersion of thermo-optic coefficients for some optical glasses
Sellmeier coefficients and dispersion of thermo-optic coefficients for some optical glasses
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DOI：
10.1364/ao.36.001540
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发表时间：
1997-03-01
期刊：
影响因子：
1.9
通讯作者：
Ghosh, G
中科院分区：
文献类型：
--
作者：
Ghosh, G
用两个独立的物理模型分析了十多种重要的肖特和大原光学玻璃的折射率及其随温度的变化，即热光系数(dN/dt)，以求出在整个透射区内任何波长在任何工作温度下的折射率。用两极Sellmeier方程对折射率的室温目录值进行了拟合。平均电子吸收带隙和晶格吸收频率分别位于真空紫外区和红外区，对折射率及其色散有贡献。估算的吸收带隙为8.5-11.9 eV，与正常光学玻璃在8.8-11.6 eV的测量值符合得很好。高折射率玻璃在5.6-6.3 eV范围内有电子吸收，SF6玻璃的带隙估计为6.0 eV。根据真空紫外区的热膨胀系数、激子带隙和等熵光学带隙这三个物理参数，用一个模型较好地解释了热光系数的色散。这些光学常数被用来计算在任何工作温度和波长下的折射率。根据计算的光学常数估算了这些玻璃的阿贝数和色散特性，特别是在光纤通信系统和飞秒技术的三个光学窗口中估算了色散的大小。(C)1997年美国光学学会。
The refractive index and its variation with temperature, the thermo-optic coefficient (dn/dT), are analyzed with two separate physically meaningful models for more than a dozen of some important Schott and Ohara optical glasses to find the refractive index at any operating temperature for any wavelength throughout the transmission region. The room-temperature catalog values of refractive indices are fitted with a two-pole Sellmeier equation. Both the average electronic absorption band gap and the lattice absorption frequency, lying in the vacuum UV and IR regions, respectively, contribute to the refractive indices and their dispersion. The estimated absorption band gaps are at 8.5-11.9 eV, and these values agree with the measured values at 8.8-11.6 eV satisfactorily for normal optical glasses. The higher-index glasses have electronic absorption in the region of 5.6-6.3 eV, and the estimated band gap of SF6 glass is 6.0 eV. The dispersion of thermo-optic coefficients is accounted for satisfactorily with a model, based on three physical parameters, the thermal expansion coefficient and excitonic and isentropic optical band gaps that are in the vacuum UV region. These optical constants are used to compute refractive indices at any operating temperature and wavelength. The Abbe number and the chromatic dispersion characteristics of these glasses are evaluated from the computed optical constants; the values of the chromatic dispersions are evaluated particularly at the three optical windows of the optical fiber communication systems and femtosecond technology. (C) 1997 Optical Society of America.