Measurements of the refractive index of PbEuTe in the 3–10-μm region of the infrared

The refractive index is measured for PbEuTe alloys in the 3.3-12-microm spectral region. Each alloy is grown with a different Eu concentration. The range of Eu concentrations studied is between 0.76 and 6.5 at. %. All measurements are performed on samples maintained at room temperature. We use a classical dispersion relation to establish a simple empirical relationship that describes the dependence of the refractive index as a function of both the percentage of the Eu concentration and the infrared wave number.