Femtosecond transient grating effect and stoichiometry of TeO2–Nb2O5–TiO2 glass

We observed efficient transient optical grating effect from the TiO2–Nb2O5–TeO2 glasses excited by femtosecond laser pulses. The glass samples were prepared via melt-quenching technique. The optical nonlinearities were calibrated by forward degenerate four wave mixing (DFWM) experiment with 50 fs laser pulse at 800 nm. The magnitude of the third order nonlinear susceptibility χ(3) was about 7–9 × 10− 13 esu, and its temporal response is up to the resolution limit of the laser 50 fs pulse-width. It has been found that χ(3) is critically dependent on the stoichiometry of between TiO2 and TeO2. The results of Raman experiment have indicated that TiO2 dopant induces transformation from the [TeO4] unit into [TeO3] via [TeO3+1], and it results in reinforcement in the rigidity of the glass network so that the χ(3) was suppressed.