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

Optical absorption and emission spectra are measured on Nd3+ ion in near-stoichiometric LiNbO3 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 LiNbO3:Mg, Nd system. The induced emission cross sections are calculated to be 2.70x10(-19) and 5.57x10(-20) cm(2) for the pi and sigma polarizations, respectively, based on the decomposition of the polarized spectra. These values agree well with the reported values of 1.8x10(-19) and 5.1x10(-20) cm(2) for the pi and sigma 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 2.0x10(16) for the Nd(2 wt %) near-stoichiometric LiNbO3:Mg, Nd in the pi polarization, the value of which is almost the same as that of 1.5x10(16) for Nd:Y3Al5O12, one of the representative laser materials. (c) 2006 American Institute of Physics.