Crystalline phase, profile characteristics and spectroscopic properties of Er3+/Tm3+-diffusion-codoped LiNbO3 crystal

Abstract

Er3+/Tm3+-codoped LiNbO3 crystal was prepared by co-diffusion of stacked Er and Tm metal films coated onto surface of off-congruent, Li-deficient LiNbO3 substrate produced by Li-poor vapor transport equilibration technique. The crystalline phase on the diffused surface was analyzed by X-ray single-crystal diffraction. The Er3+ and Tm3+ profile characteristics were studied by secondary ion mass spectrometry. The emission spectra were measured under the 980 or 795nm wavelength excitation, and the emission and absorption cross section spectra were calculated based upon McCumber theory. The lifetimes of some emissions were measured. The results show that the Er3+ and Tm3+ ions presence is in the form of LiNbO3 phase. Both ions obey to Gaussian profile with a diffusion depth 21.5μm. In the codoping case, both ions keep their respective spectroscopic features of only doping case and do not affect each other. The codoping enables to combine the wavelength emissions of both ions and the resultant emission band in the telecommunication window around 1.5 μm is as wide as 150nm, providing the possibility of S+C+L broadband amplification by employing commercial 980 and 795nm laser diodes as the pump sources. The Er3+/Tm3+-codoped LN is a promising host material for integrated optics.