Luminescence properties and optical dephasing in a glass-ceramic containing sodium-niobate nanocrystals

Photoluminescence (PL) and degenerate four-wave-mixing (DFWM) experiments were performed in a silica-niobic composite containing NaNbO3 nanocrystals. The PL results indicate the presence of in-gap states attributed to excitons in the nanocrystals and defect centers. The luminescence of the samples becomes more intense at low temperatures, indicating that nonradiative relaxations dominate the dynamics of the in-gap states. The DFWM experiments allowed for measurements of the homogeneous relaxation time, (20 +/- 3) fs, of the third-order polarization at room temperature. The main contributions to the dynamics of the electronic response are attributed to the trapping of electrons in the in-gap states and to carrier and phonon scattering. (C) 2011 American Institute of Physics. [doi:10.1063/1.3596518]