用两段式波导模型研究3dB宽带光纤耦合器

Study on 3dB Wide Band Coupler in Two-Type Waveguide Model Gu Bingsheng

报道了用两段式组合波导模型分析研究３ｄＢ宽频带熔锥型单模光纤耦合器．根据文献［１］用两根阶跃型单模光纤，使其中一根光纤的熔锥区腐蚀变细，熔融拉锥成两段式的准双锥体组合波导，分别用变分理论和传统的耦合波理论分析横截面近似不变的腰部区域和横截面随纵向距离变化的梯度区域内的耦合行为，耦合器的耦合功率应是这两段区域耦合功率的叠加．从而得到了耦合器中任意点的耦合功率表达式．用光纤参数和适当的组合波导横截面尺寸计算不同波长的耦合长度Ｚｃ，据此找到宽频带的耦合长度Ｚ０通过分析比较，得到了一种符合工艺实际且具有相当平坦功率谱的熔融型单模光纤耦合器．

This poper describes the study on 3 dB wide hand coupler in two-type waveguide model. Two fibers of stepping refraction index were used. ho coupling zone of one fiber become thin by etch method, to make a combination waveguide of two quasi cone shaped. The variational and coupled wave theory, are adoped to analyse the waistzone and trapezvidal zone. Toeal POwer was equal to the sum of two pet coupled power at any POint of the coupler. Using parameter of fiber and she of combination waveguide transverse section tO compute the compeled length 4 at 1. 57 μm and 1. 39 μm wavelength, thus coupled length for wide band, ic was obtained. Through analyse andcompovison proved that this theory suit technological practice. A single mode optical fiber coupler with flat power-spectrum and technological feasibility was achieved.