Upconversion luminescence properties of Er³⁺ ions doped in lithium niobate single crystals

Abstract

Laser selective excitation is used to study the spectroscopic properties of Er³⁺ ions doped in Lithium Niobate (LNB) single crystals, where it substitutes for the Li+ or Nb5+ sites both having local C3 symmetry. Excited state absorption resulting in energy upconverted fluorescence 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 excitation and emission spectra of the upconverted fluorescence reveal the existence of multiple sites and inhomogeneously broadened energy levels as a consequence of the disordered structure of the LNB lattice.

Key Words:

• Kew words:Er
• LiNbO₃
• upconversion.