UP-CONVERSION LUMINESCENCE PROPERTIES OF ER3-NIOBATE SINGLE-CRYSTALS(IONS DOPED IN LITHIUM)

Laser selective excitation is used to study the spectroscopic properti es of Er3+ ions doped in Lithium Niobate (LNB) single crystals, where it substitutes for the Li+ or Nb5+ sites both having local C-3 symmetr y. Excited state absorption resulting in energy upconverted fluorescen ce are observed (for dopant concentrations range 0.045 to 0.37 mol.%) for temperatures up to 297 K. The upconversion mechanism is dominated by the sequential two photon excitation process. The polarised excitat ion and emission spectra of the upconverted fluorescence reveal the ex istence of multiple sites and inhomogeneously broadened energy levels as a consequence of the disordered structure of the LNB lattice.