Induced emission cross sections of near-stoichiometric LiNbO3: Mg, Nd

Abstract

Optical absorption and emission spectra are measured on Nd3+ ion in near-stoichiometric LiNb O3 single crystals codoped with MgO. From the decomposition of the nonpolarized spectra, the Stark splitting scheme is established for 2 wt % Nd3+ ion in the near-stoichiometric LiNb O3: Mg, Nd system. The induced emission cross sections are calculated to be 2.70× 10-19 and 5.57× 10-20 cm2 for the π and polarizations, respectively, based on the decomposition of the polarized spectra. These values agree well with the reported values of 1.8× 10-19 and 5.1× 10-20 cm2 for the π and polarizations of the conventional congruent-melt composition crystal through the branching ratio of emission spectra despite the different approach of calculations and difference in the near-stoichiometric and congruent-melt compositions. This fact shows that the slight difference in the host composition does not affect the cross section. The population inversion threshold is calculated to be 2.0× 1016 for the Nd (2 wt %) near-stoichiometric LiNb O3: Mg, Nd in the π polarization, the value of which is almost the same as that of 1.5× 1016 for Nd: Y3 Al5 O12, one of the representative laser materials. © 2006 American Institute of Physics.