Optical properties of Mg²⁺, Yb³⁺, and Ho³⁺ tri-doped LiNbO₃ crystals

A series of LiNbO₃ crystals tri-doped with Mg²⁺, Yb³⁺, and Ho³⁺ are grown by the conventional Czochraski technique. The concentrations of Mg²⁺, Yb³⁺, and Ho³⁺ ions in Mg:Yb:Ho:LiNbO₃ crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO₃ crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy (E_r) is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO₃ crystal is 709.17 J/cm², approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO₃ crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO₃ crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO₃ crystal can be applied to the fabrication of new multifunctional photoluminescence devices.