为产生全光域UWB(超宽带)一阶和二阶信号, 降低光载UWB系统成本, 提出了一种基于偏振调制同时光生一阶和二阶UWB信号的方法。将两路极性相反的高斯脉冲信号通过PolM(偏振调制器)相位调制到偏振态正交的两个光载波上, 利用PMF(保偏光纤)引入适当的群延时, 生成一阶UWB信号。通过PC(偏振控制器)控制输入光信号与PMF主轴所成的角度, 产生一对极性相反的一阶UWB信号, 并对其中一路进行适当的延时, 合成后即可生成二阶UWB信号。所得一阶UWB信号的中心频率为5.36 GHz, -10 dB绝对带宽为8.96 GHz, 相对带宽为167%; 二阶UWB信号的中心频率为5.83 GHz, -10 dB绝对带宽为7.36 GHz, 相对带宽为126%, 均满足FCC(美国联邦通信委员会)标准。分析了偏振调制中时延对生成的UWB信号性能的影响。结果表明, 当偏振调制中引入的时延τ=TFWHM时, 生成的二阶UWB信号更符合FCC要求。

To generate all-optical domain monocycle UWB and doublet signals, and reduce the cost of UWB over-fiber system,a methodbased on polarization modulationisproposed. Two Gaussian pulses with opposite polarity arephase-modulated to theorthogonal optical carrierswith the Polarization Modulator (PM).Then an appropriate group delayis introduced by Polarization Maintaining Fiber (PMF) to generate monocycle UWB signal. By changing the angle between the signal polarization direction and PMF principal axis, two monocycles UWB with opposite polarity can be generated. Then by introducing appropriate time delay to one of them before the combination of the two monocycles UWB, a doublet UWB can be obtained. Monocycle and doublet UWB have a central frequency about 5.36 GHz and 5.83 GHz, a -10 dB bandwidth about 8.96 GHz and 7.36 GHz, and a fractional bandwidth about 167 % and 126 %, which both meet the FCC standards. The performance effects of the delay are analyzed. The result shows that when τ=TFWHM, the generated doublet UWB signal meets the FCC standards best.