双折射对孤子传输的影响及其相互作用控制

Influence of birefringence in optical fiber on optical soliton transmission and the interaction controlling

利用对称分步傅里叶法,数值研究了双折射光纤中孤子的传输特性,分析了孤子脉冲的入射偏振角为30°时两偏振分量群速度失配对孤子传输产生的影响。结果表明,光纤的双折射大小影响着脉冲峰值对时间的漂移程度,双折射越大,峰值漂移越多。如果光纤的双折射具有随机性,峰值漂移被修正,孤子传输的两偏振分量脉冲强度会随着传输距离有强弱不规则的变化,但是两偏振分量的强度变化互相补充,合成强度没有太大的变化,孤子能够稳定的传输。非线性增益可以有效地抑制随机双折射对孤子传输相互作用的影响,使得原本会产生交叠走离的相邻孤子传输不偏离原来的时间槽,实现了对偏振模色散良好的控制作用。

In this paper,symmetrical slit-step Fourier numerical method is used to simulate the soliton transmission properties in the fibers presenting birefringence.When the polarization angle of incidence is 30 °,the inferences of the group velocity mismatch which denotes the magnitude of the birefringence on the soliton transmission are analyzed.It is shown that the magnitude of birefringence affects the drift extent of pulse peak on the time-axis.The larger the birefringence,the longer the drift will be.If the birefringence of the fiber is randomly varying,the drift of the pulse peak will be corrected.The intensity of the two polarization component of the soliton change irregularly with the transmission distance but the composite intensity of the soliton pulses hardly varies because the two polarization component compensate each other.The randomly varying birefringence enhances the interaction of the soliton,but the non-linear gain can effectively inhibit the interaction of soliton transmission.That makes the adjacent solitons which tend to be overlapping and separating to avoid deviating from the original time slot.It achieves a good control over polarization mode dispersion.