自准直干涉仪测量光纤非线性克尔系数的参数优化

Parameter Optimization Measuring Nonlinear Kerr Coefficient Using Self-aligned Interferometer

理论上分析了以抗干扰很强的干涉法测量光纤非线性克尔系数γ的装置。这种装置由M-Z干涉仪组成。它是一种自补偿系统,可很好地解决环境引起的相移波动。由于测试脉冲强度受光纤衰减和耦合器分流的影响,输入段和输出段脉冲强度不一样,势必要引入系统相移扰动,造成与测试光纤SPM效应引入的相移并非一致的测试相移,这对准确测量光纤非线性克尔系数γ值形成误差。理论导出扰动相移误差量。模拟分析了影响相移误差量的参数,优化这些参数,并且找到最优参数值,使相移误差量最小。

The setup has been theoretically analyzed based on self-aligned interferometer, which consists of Mach-Zehnder （M-Z） interferometers used to measure optical fibers Kerr coefficient. The setup is insensitive to environmental perturbations. However, the phase shift isn＇t completely induced by self-phase modulation（SPM） of tested fibers, and there are some other phase shifts created by the fibers of the system. Since the pulses intensities are different between a forward pass and a return pass, and there is excessive phase shift, it is impossible to measure the optical fibers Kerr coefficient accurately. In the setup, a new parameter A which expresses the error of nonlinear phase shift is defined, the system parameter has been analyzed and optimized to obtain the minimum Δ.