利用镁离子内扩散铌酸锂单晶光纤,实现了晶纤具有芯-包层波导结构,得到了包层晶纤的损耗比扩镁前晶纤损耗降低约14倍的好结果,并对镁离子内扩散机理、晶格发生畸变的原因等进行了分析和讨论。通过X射线衍射分析和扫描电子显微镜观察扩镁表面,发现在表面富镁层有一新化合物结构,可能是Li-Mg-Nb-O组成的三元系相结构,并提出和实验证实这一富镁层的新化合物是镁离子内扩散铌酸锂晶纤的真正扩散源。 The use of magnesium ion diffusion lithium niobate single crystal fiber, the realization of a fiber core-clad waveguide structure, get the cladding crystal fiber loss than before magnesium fiber loss reduced by about 14 times the good results, and magnesium Ion diffusion mechanism, lattice distortion causes were analyzed and discussed. By X-ray diffraction analysis and scanning electron microscope observation of the magnesium surface, a new compound structure was found on the Mg-rich surface, which may be the ternary phase structure of Li-Mg-Nb-O. Magnesium layer of the new compound is a magnesium ion diffusion lithium niobate fibers of the true diffusion source.