光纤定向耦合器的开关特性研究

Study on the Switching Performance of Fiber Directional Coupler

摘要:

基于耦合非线性薛定谔(NLS)方程组, 利用分步傅里叶法(SSFM), 研究了二阶色散长度与线性耦合系数的乘积L_Dκ、三阶色散长度与线性耦合系数的乘积L′_Dκ以及模间色散(IMD)对双芯非线性光纤定向耦合器开关特性的影响。研究表明, 在光纤正常色散区, 当入射功率大于阈值功率时, 从波导1到波导2有明显的能量转移, 耦合器的开关性能差;而在光纤反常色散区, 当L_Dκ<1时, 非线性定向耦合器(NLDC)能够表现出良好的开关特性。且阈值功率随着L_Dκ<1的增大而减小。当|IMD|≤0.01, IMD对NLDC开关特性的影响可以忽略。当|IMD|=0.2, 且L_Dκ的值较小时, 在入射功率大于阈值功率的条件下, IMD对开关特性的影响不明显;而在入射功率小于阈值功率时, 耦合器的开关特性下降。此外, 三阶色散(TOD)效应对NLDC的影响通常可以忽略。

Abstract:

Based on the coupled nonlinear Schrodinger (NLS) equations and the split-step Fourier method (SSFM), studied are the effects of as the productL_Dκ of the second-order dispersion length with linear coupling coefficient, as the product L′_Dκof the third-order dispersion length with linear coupling coefficient, and the mode dispersionon (IMD) on the switching performance of dual-core nonlinear fiber directional coupler. Studies show that in the normal dispersion region, the energy transfer efficiency from the launched waveguide to the adjacent waveguide is still significant when the input power is greater than the threshold power, and the switching performance is poor. While, in the anomalous dispersion region, NLDC can get a good switching performance when L_Dκ<1. And the threshold power decreases with the increase of L_Dκ<1. In the case of |IMD|≤0.01, the influence of IMD on the switching performance of NLDC is negligible. When |IMD|=0.2 and the L_Dκ is small, the influence of IMD on the switching performance is insignificant if the input peak power is larger than the threshold power. However, the switching performance degrades due to IMD if the input peak power is less than the threshold power. In addition, the influence of the third order dispersion(TOD) on the switching performance is negligible.