光纤纤芯及包层模有效折射率计算及仿真

Calculation and simulation of optical fiber core and cladding mode effective refractive index

光纤结构设计、模间色散求解、光纤光栅模式耦合等问题的研究,都需要对光纤纤芯及包层模的有效折射率进行精确计算.本文以光纤三层结构模型为基础,结合该模型下的模式本征方程,使用截弦法求解了纤芯模有效折射率,并将计算结果与COMSOL软件模拟的对应纤芯模的传输光场进行对比,验证了计算结果正确.使用区间遍历算法对包层模有效折射率进行了求解,与已有的传统方法相比,该方法可以有效防止求解过程中根的遗漏、避免特征方程产生的奇点,并能保证模式的正规性.本文采用Mathematica软件对求解过程进行仿真,获得了纤芯模和包层模有效折射率与波长关系曲线.

The accurate computation of effective refractive index of optical fiber core and the cladding mode are needed for the fiber structure design, mode dispersion analysis and fiber grating mode coupling research. In this paper, based on three layered optical fiber waveguide model and its accurate eigenvalue equation, by using the cut string algorithm the effective refractive index of core mode is solved. At the same time the computation results are verified by using COMSOL software. By using interval traversal algorithm the effective refractive index of cladding mode is computed. Compared with the existing algorithms, this method can avoid the loss of root during the calculation. It can also avoid the generation of odd point and can keep the normality of each mode. The simulation is based on Mathematica software. The curves relating effective refractive index of core and cladding mode to wavelength are obtained.