Search

Er 3+ /Ti 4+ -co-doped LiNbO 3 plates were prepared by annealing congruent substrates coated with stacked Er- and Ti-metal films having different thicknesses and coating sequences. The crystalline phase, OH − absorption, Er 3+ -doping effect on LiNbO 3 refractive index and Li + -composition in the Er 3+ /Ti 4+ -co-doped layer were studied. The results show that the LiNbO 3 phase dominates in the co-doped layer, the Er 3+ -doping affects little the LiNbO 3 refractive index, slight Li 2 O out-diffusion occurred in the diffusion procedure, and the annealing procedure does not affect the OH − absorption band noticeably. The Er 3+ /Ti 4+ -co-diffusion characteristics were studied by secondary ion mass spectrometry. The study shows that Ti 4+ diffuses much faster than Er 3+ . The Ti 4+ co-diffusion assists and controls the Er 3+ -diffusion and Er 3+ diffusivity increases linearly with initial Ti-metal thickness. In contrast, neither Er-metal thickness nor coating sequence of Ti- and Er-metal films influences the Ti 4+ or Er 3+ diffusivity. The co-diffusion features are explained. A co-diffusion model is proposed. [ABSTRACT FROM AUTHOR]

Multi-mode Ti:LiNbO 3 planar waveguide was fabricated by in-diffusion of 100-nm-thick Ti-metal film coated onto a near-stoichiometric LiNbO 3 substrate prepared by vapor transport equilibration. The crystalline phase and composition in the waveguide were characterized. The guided modes in the planar waveguide were characterized by prism coupling technique. The refractive index profile is constructed from the measured mode indices using the inverse Wentzel–Krames–Brillouin method, and correlated with the Ti 4+ - concentration profile, which was obtained from secondary-ion-mass-spectroscopy analysis. The results show that the waveguide still retains the LiNbO 3 phase, its composition is near-stoichiometric. The index change and Ti 4+ -concentration follow an exponential relationship with a power index 0.4 for an ordinary ray and 1.07 for an extraordinary ray. A comparison of various congruent and near-stoichiometric bulk materials or waveguides allows to conclude that the relationship is different from congruent to near-stoichiometric composition, from one fabrication method to another, and from bulk material to waveguide configuration. The difference is explained qualitatively. [ABSTRACT FROM AUTHOR]