The Ti dopant occupying Li or Nb sites and the charge transfer processes induced by thermochemical reduction and optical bleaching treatments have been investigated in LiNbO3 systems using optical absorption and EPR. The Ti3+ centers, built preferentially at Nb sites in heavily Mg-codoped crystals, are shown to have absorption bands at 1.62 ±0.08 eV and 2.65 ±0.25 eV, which are similar or slightly redshifted compared to Ti 3+ centers at Li sites in LiNbO3: Ti crystals. The Ti nb4+/3+ gap level plays an important role in the trapping of electron-polarons in LiNbO3, double-doped with Mg and Ti; in particular, an enhanced optical detrapping sensitivity for pumping in the 1.3-2.8 eV range is observed, which may be relevant for applications in integrated optics. Evidence indicating the possible existence of bipolarons involving the Ti dopant is presented.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)
- Physics and Astronomy(all)