光致折变Taper光纤耦合器的耦合波分析

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．

Coupled Wave Analysis of an Optical Refractive Index TaperedFiber Coupler by UV Irradiation

We discussed the mode coupling in an optical fiber tapered coupler with itsrefractive index gradually changins along its propagation axis caused by photo-inducedrefractive effect.Under scalar approximation,the field in the stead index fiber andparabolic-index fiber tapers is expressed in local normal modes to analyze the coupling of thefundamental mode to its reflected one in opposite direction and high-order ones in codirection. The numeric resultS for two different taper profiles in step-index fiber show thatthe couplings to the reflected mode and the high-cider modes are relatively small providedthe change is gradual,and the fundamental mode has the capability of excellent transmissionwhich can adjure itself adiabatically to the reflective index change.