Generalized anisotropic ellipsometry applied to an organic single crystal: Potassium acid phthalate

The results of generalized anisotropic ellipsometry on a biaxial organic single crystal, namely, potassium acid phthalate, are discussed and analyzed to obtain the optical functions of the crystal along the different crystal directions. The dispersion of the real refractive indices $n_x,$ $n_y,$ and $n_z$ in the spectral range from 300 to 1400 nm, as well as the values of the extinction coefficient $k_{\mathrm{x,y}}$ at the absorption edge are determined and modeled.