Applicability of the constitutive equations for the determination of the material properties of optically active materials

For the description of the optical response of optically active media, different constitutive equations have been proposed and are still used in literature. Here, we demonstrate on potassium titanyl phosphate (KTiOPO4) by means of ellipsometry that only the symmetric constitutive equation describes the observed spectra properly and allows the unique determination of the gyration tensor.