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研究利用光纤中光致折变效应研制的光纤波导折射率沿轴向渐变的Ｔａｐｅｒ器件的模式耦合特性．在标量场近似下，用本地模表示的方法分析在阶梯折射率分布光纤和平方律折射率光纤的轴向折射率渐变过渡结构中传输的基模向反向散射模和高价模的耦合。对阶梯折射李光纤两种不同折射率Ｔａｒｅｒ结构的数值计算结果表明：在折射率变化相对缓慢情况下，这种折射率Ｔａｐｅｒ耦合器的基模反向散射和向高阶模的耦合都很小；基模能够自适应地调节以适应波导折射率的渐变，具有优良的传输性能．
The mode coupling characteristics of tapered Taper devices with refractive index of optical fiber waveguide developed by photorefractive effect in optical fiber are studied. In the scalar field approximation, the coupling of the fundamental mode backscattering mode and the high-order mode propagating in the axial refractive index gradient transition structure of the stepped refractive index distribution fiber and the square-law refractive index fiber is analyzed by the local mode representation. The numerical results of two different refractive index Tarer structures for the stepped refracted Li fibers show that the fundamental mode backscattering and the coupling to the higher order modes of the refractive index Taper coupler are very small when the refractive index changes slowly. Modulation can be adaptively adjusted to accommodate the gradual change of refractive index of the waveguide, with excellent transmission performance.