基于两个平行马赫-增德尔调制器的光载无线传输系统

A radio over fiber transmission system based on two paralleled Mach-Zehnder modulators

为提高光载无线(radio over fiber,RoF)传输系统中的光波信号的利用率,本文提出了一种基于两个平行马赫-增德尔调制器(Mach-Zehnder modulator,MZM)的RoF传输系统。两个平行MZM经射频(radio frequency,RF)信号调制后,产生5个光边带信号,分别是正负一阶光边带、正负二阶光边带和光载波。其中正负二阶光边带使用基带数据进行调制,经光电检测器(photodiode,PD)拍频后产生已调数据的毫米波信号,再由天线发射出去。正二阶边带和光载波经PD拍频后产生未调制数据的毫米波,该毫米波用于接收端解调的本振信号(local oscillator,LO)。负二阶边带信号用于上行链路的光载波。在本系统中,5个光边带信号都被充分利用,提高了光信号的利用效率。此外,还分析了该系统通过色散介质的传输特性,为RoF通信系统提供了一种实用化的解决方案。

In order to improve the utilization rate of optical signals in radio over fiber(RoF)system,a RoF system based on two paralleled Mach-Zehnder modulators(MZM)is proposed.The two paralleled MZMs are modulated by radio frequency(RF)signal and five optical sideband signals can be generated,which are±1*order sidebands,±2nd order sidebands and optical carrier.±2nd order optical sidebands are modulated by baseband data,millimeter(mm)-wave signals with modulated data can be generated after beating by photodiode(PD),which can be emitted by aerials.+2nd order sideband and optical carrier are used to generate the mm-wave signals without modulated data after beating by PD,this mm-wave signals can be used as the local oscillator(LO)for the demodulation of receiving end.-2nd order optical sideband is used as the optical carrier for uplink.In the proposed scheme,the whole five optical sideband signals are fully utilized,the utilization rate of optical signals is improved.In addition,the analytical models for transmission through a dispersive medium are confirmed.Results show that such a scheme can offer a realistic solution for RoF system.