基于光纤XPM光学生成UWB信号的方法

提出了一种基于色散位移光纤(DSF)的交叉相位调制(XPM)效应的超宽带(UWB)光学生成方法。该方法首先利用DSF的XPM效应实现高功率的高斯泵浦光对低功率的直流探测光的交叉相位调制,然后利用光纤布拉格光栅(FBG)对探测光进行鉴频,实现相位调制到强度调制的转换,从而获得单周期UWB信号。利用光子仿真软件对方案进行了仿真实验,得到了中心频率分别为7GHz和6.95GHz、相对带宽分别为143%和145%的UWB信号,验证了所提方法的可行性。同时,研究了输入信号脉冲宽度、FBG的反射率、鉴频器的类型对产生的单周期UWB脉冲信号波形和频谱的影响。仿真实验的结果表明,该方案对输入信号脉冲宽度不是过宽的情况下具有良好的容忍度,光学高斯带通滤波器、波分复用器和FBG等光滤波器均可作为鉴频器,采用FBG优点是可通过改变反射率灵活地调整产生的UWB脉冲信号的波形。

A Method of Optical UWB Pulse Generation Based on XPM in Dispersion Shifted Fiber

A method for generating ultra-wide-band (UWB) pulse is proposed based on cross-phase modulation (XPM) in dispersion shifted fiber (DSF). In this method, the low-power continuous wave probe light is phase modulated by the high-power pump light using the XPM in DSP, then the following fiber Bragg grating (FBG) is served as a frequency discriminator to convert the PM to IM. Finally, a monocycle UWB signal is achieved. By using the software of Optisystem7.0, and two UWB pulses with the center frequencies at 7GHz and 6.95GHz, and the fraction bandwidths as 143% and 145% are obtained. The impacts of the input signal pulse width, the reflectivities of FBG and the different frequency discriminators on the generated UWB monocycle pulse are numerically simulated and studied. The results show that this scheme has good tolerance to the input signal pulse width. Optical Gaussian band-pass filters, wavelength division multiplexer and FBG can be used as the frequency discriminators. FBG has more advantages due to the flexibility of adjusting the waveform of the generated UWB pulse signal by changing the reflectivities of FBG.