对于半导体光放大器(SOA),当输入光功率和SOA的饱和功率可比拟时,SOA表现出较强的非线性效应,包括自相位调制(SPM)和交叉相位调制(XPM)。SPM会使光谱在信号中心频率附近展宽,而XPM会在探测光附近产生新频率的光。链路中不同色散值会使输入光的峰值功率产生变化,从而在SOA中会产生不同程度的SPM和XPM效应。通过合理地设置滤波器的中心频率和带宽,同时测量由SPM和XPM效应产生的频谱变化结果,来达到对链路中残余色散(CD)进行监测的目的,色散监测范围可达±30 ps/nm以上。该技术可以实现对链路中残余色度色散和偏振模色散(PMD)的监测。

When the input optical power is comparable with the saturated power of the semiconductor optical amplifier (SOA),SOA has a large nonlinearity,including self phase modulation (SPM) and cross phase modulation (XPM). SPM makes the signal′s spectrum broaden around the central frequency;XPM produces new frequency parts around the probing light. The different dispersions of the link will change the signal peak power differently,leading to the varied effects of SPM and XPM in SOA. Via effectively setting the central frequency and bandwidth of the filters,the different spectrum changes related to SPM and XPM can be detected simultaneously,in order to monitor the link dispersion,whose range may be over ±30 ps/nm. This technique can be used to monitor the residue chromatic dispersion (CD) and polarization mode dispersion (PMD).