对特征方程直接求导解得了基模群时延和群速色散,讨论了双包层单模光纤不同折射率分布对传播常数、群时延、群速色散以及零色散点波长的影响.研究结果表明:光学参数,即纤芯和外包层的相对折射率(P)以及内包层和外包层的相对折射率(R)对该类光纤的传播常数、群速度、群速色散和零色散点波长均有比较明显的影响,影响的大小及规律随参数的不同又有所不同.这些规律为设计满足不同色散要求的双包层单模光纤提供了理论依据.

The group delay and group velocity dispersion (GVD) of the fundamental mode was proposed by derivative action on the characteristic equation directly and the influence of different index contribution of doubly clad single-mode fibers on propagation constant, group delay, group velocity dispersion and the zero dispersion wavelength were studied. The research results indicate that the optical parameters, i.e., relative index of inner clad and outer clad (R) and relative index of the core and outer clad (P), have distinct impact on propagation constant, group delay, group velocity dispersion and zero dispersion wavelength and the rules of impact vary with the parameters. These rules provide theoretical basis for designing doubly clad single-mode fibers catering for different dispersion.