Yb Sensitized Near-Stoichiometric Er:LiNbO₃ Single Crystal: A Matrix for Optical Communication and Upconversion Emission

Abstract

Ytterbium and erbium codoped crystals have attracted considerable interest in the application of eye-safe laser, upconversion laser, and low-loss optical communication. Despite the lithium niobate (LiNbO3, LN) single crystal has been accepted as an ideal crystal matrix for Yb3+ and Er3+ ions possessing significant application potential in self-upconversion laser, the Yb and Er codoped near-stoichiometric LN (NSLN) crystal has rarely been studied. This is due to the difficulty of the NSLN crystal growth compared with that of the congruent LN (CLN). In this paper, an Yb, Er codoped near-stoichiometric LN (Yb, Er:NSLN) crystal was grown by the Czochrolski method for the first time. Spectra studies showed the constrained peak splitting at 378, 526, and 650 nm of the Yb, Er:NSLN crystal compared with Yb, Er:CLN crystal. It was attributed to the low concentration of intrinsic defects which constrained the Stark-split of the three energy levels of 4G11/2, 2H11/2, and 4F9/2 energy states. Some spectral changes are verified induced by the stoichiometric composition in the polarized emission spectra. The Yb, Er:NSLN crystal has high potential in upconversion laser application.