Yu, Yiting Ge(n,k).csv The supplementary material gives the complex refractive index (n, k) of Ge measured by the spectroscopic ellipsometry. Plasmonics and Optics at Surfaces 2019-02-08
    https://opticapublishing.figshare.com/articles/dataset/Ge_n_k_csv/7581548
10.6084/m9.figshare.7581548.v1