为提高耦合波导系统的透明度，文章重点分析了波导损耗、非线性以及周期调制参数对系统性能的影响。在弱波导理论近似下，采用龙格-库塔算法数值求解非线性薛定谔方程，发现随着耦合波导损耗的增大，输入波导的透明度表现出先衰减而后增强的反直觉现象。进一步研究表明，提高输入波导的非线性强度，可以有效地提高输入波导中的光强分布，表现为光信号透明度的增强，该研究结论对于普通耦合系统和周期调制系统具有普适性。因此，提高输入波导的非线性，增强耦合波导的损耗，并对输入波导进行适当的周期调制，可以获得最大的透明度。

To enhance the transparency of coupled-waveguide system, this paper analyze the influence of waveguide loss, nonlinearity and the modulation parameters on the system performance. In the approximation of weak-waveguide theory, the nonlinear Schrdinger equations are solved numerically by Runge-Kutta method and the results show that with the increase of the coupled-waveguide loss, the transparency of input waveguide will decrease firstly and then increase counter-intuitively. Further results indicate that the power distribution of input waveguide can be enhanced effectively by increasing the nonlinearity of input waveguide. In this way, the effect of transparency is enhanced. Our results are universal for ordinary coupled systems and periodic modulation systems. Therefore, the maximum value of transparency can be obtained through increasing the nonlinearity of input waveguide and coupled-waveguide loss while the input waveguide is modulated periodically with appropriate parameters.