基于三角波调制的毫米波光学倍频发生器

A millimeter-wave optical frequency multiplication generator by using triangular pulse sweep

提出一种使用双极马赫-曾德尔调制器(De-MZM)作为外部调制器,利用三角波调制得到各阶边带组成的调制信号的毫米波光学倍频(OFM)发生器.使用中心波长可调节的均匀光纤光栅(UFBG)滤出其中两个边带拍频得到毫米波信号,提高了生成毫米波信号信噪比,并实现了毫米波频率的可调谐.与传统的OFM发生器相比较,该发生器可以在较低的调制深度下得到较大的倍频因子,避免高频本地振荡器的使用,减少了系统成本并增加了系统稳定性,实现了倍频因子的可调谐.当倍频因子为10时,仍能获得信噪比较高毫米波信号.为了验证此发生器的可行性,仿真生成了60 GHz、80 GHz和100 GHz的毫米波信号,且60 GHz毫米波信号的信噪比达到了35 dB.并且基于60 GHz毫米波分析了光载无线电系统(Radio Over Fiber,ROF)下行链路的传输性能,当传输距离达到60 km时,眼图仍能保持较好的张开度,证明了本发生器在实际应用中的可行性.

A millimeter-wave optical frequency multiplication generator,in which a dual-electrode Mach-Zehnder modulator driven by triangular pulse is used as external modulator,is proposed.In the generator,high order harmonics can be generated.By using two cascaded uniform fiber Bragg gratings,two of the harmonics can be filtered to generate millimeter-wave signal.In addition,the multiplication factor can be tunable by adjusting the central frequency of two uniform fiber Bragg gratings respectively.Compared with traditional optical frequency multiplication generator,the proposed one has many advantages,such as tunable frequency,cost-efficiency,higher signal to noise ratio and stability.This generator is verified by simulation.In the simulation,millimeter-wave signal with frequency of 60GHz,80GHz and 100GHz are generated and the signal to noise ratio of 60 GHz millimeter-wave is 35dB.Based on the 60GHz mm-wave generation,the system transmission performance is evaluated.After 60km transmission,the eye diagram is still open and results show that the system is reliable and effective.