Nonlinear optical susceptibility of multicomponent tellurite thin film glasses

摘要

Tellurite (TeO_2-TiO_2-Nb_2O_5) thin film glasses have been produced by pulsed laser deposition. The dispersion of the real and imaginary parts of the linear refractive index has been measured in the range from 300 to 1700 nm. Films present high refractive index (n = 2.01) and reduced absorption (k<10~(-4)) at λ=1500 nm. The nonlinear third order optical susceptibility (|χ~((3))|) has been determined at four different wavelengths (600, 800, 1200, and 1500 nm). The out-of-resonance |χ~((3))| values (～10~(-12) esu) are found to be ten times higher than those of the bulk glass and 10~2 times higher than that of silica. Compositional and structural analysis reveals an increase of both the Ti atomic content and the fraction of nonbridging oxygen bonds in the deposited films. Both factors lead to a higher hyperpolarizability of the film constituents that is proposed to be responsible for the high |χ~((3))| value of the films.