One- and two-photon absorption in transition metal oxide glasses

An empirical equation is used for achieving the scaling of nonlinear two-photon absorption to optical bandgap in transition metal glasses. The relationship between the nonlinear absorption coefficient and the bandgap energy by using Tauc's parabolic band model is discussed in terms of electronic structure of constituent oxides, ionic polarizability, hyperpolarizability of cations, nonbridging oxygen bonds and the cationic bond-length approach.