Diffusion properties of Sc3+ in LiNbO3 crystal were studied, together with other two related issues: Sc3+‐doping effect on LiNbO3 refractive index and Li2O out‐diffusion arising from Sc3+ in‐diffusion. To reach the goal, some Sc3+‐doped LiNbO3 crystal plates were prepared by in‐diffusion of Sc2O3 film coated onto Z‐cut congruent substrates in air at different temperatures ranging from 1030°C to 1130°C. After diffusion, the refractive indices at the doped and undoped parts of surface were measured by prism coupling technique and the surface composition was evaluated from the measured index. The results show that the Sc3+ doping has little contribution to the substrate index and the Li2O out‐diffusion is not measurable. The Sc3+ profile was analyzed by secondary ion mass spectrometry. Some characteristic parameters such as temperature‐dependent diffusivity, diffusion constant, activation energy, and surface concentration are obtained. The Sc3+/Ti4+ co‐diffusion characteristics were also studied. Comparison shows that in the single‐diffusion case, the Sc3+ diffusivity is considerably smaller than the Ti4+ diffusivity. In the Sc3+/Ti4+ co‐diffusion case, the Ti4+ co‐diffusion results in substantial increase in Sc3+ diffusivity while the Ti4+ diffusivity changing little. The diffusion characteristics are qualitatively explained. The Ti4+‐assisted Sc3+ diffusion would be utilizable in shortening the fabrication period of an optical‐damage‐resistant Ti‐diffused LiNbO3 waveguide doped with Sc3+, and some considerations for the fabrication are given.
In this paper we report a chemical method named coordination reaction method to synthesize ZnO nanowire arreys. ZnO nanowires with the diameter about 80 nm were successfully fabricated in the channels of the porous anodic alumina (PAA) template by the above coordination reaction method. The microstructures of ZnO/PAA assembly were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the ZnO nanowires can be uniformly assembled into the nanochannels of PAA template. The growth mechanism of ZnO nanowires and the conditions of the coordination reaction are discussed. Photoluminescence (PL) measurement shows that the ZnO/PAA assembly system has a blue emission band caused by the various defects of ZnO.
We report a Ti:Er:LiNbO 3 strip waveguide with high diffusion-doped surface Er 3+ concentration. The waveguide was fabricated with a technological process in sequence of preparation of noncongruent, Li-deficient LiNbO 3 substrate by performing Li-poor vapor transport equilibration treatment on a congruent Z-cut LiNbO 3 plate, diffusion of 40-nm-thick Er metal film, and fabrication of 8-µm-wide Ti-diffused strip waveguide. The waveguide retains the LiNbO 3 phase and shows the waveguiding characteristics similar to the conventional Ti:LiNbO 3 waveguide. Secondary ion mass spectrometry study shows that the Er 3+ diffusion reservoir was exhausted and the profile is Gaussian with a surface concentration two times larger than that of the conventional Ti:Er:LiNbO 3 waveguide. The waveguide shows stable 1547-nm small-signal enhancement under the 1480-nm pumping without serious optical damage observed, and a 5-dB signal enhancement is obtained for the available coupled pump power of only 90 mW. A saturated net gain as much as 5 dB/cm is predicted theoretically.Index Terms-Ti:Er:LiNbO 3 waveguide, Er 3+ diffusiondoping, high Er 3+ concentration.
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