ROF系统中基于单个调制器的多射频操作

Multiple Radio Frequency Operation Based on a Modulator in a Radio-over-Fiber System

实验研究了一种采用单个激光源和一个双极化马赫-曾德尔调制器(MZM)产生两路不同频率光射频信号的矢量系统。通过光副载波复用,采用一个调制器和一个光载波即可将两路四相相移键控(QPSK)射频信号加载到两个不同频率的光副载波上,采用偏振复用克服不同频率光信号的串扰,实现了80 km单模光纤(SMF)的高质量信号传输。实验表明,单边带调制格式下,15 GHz和30 GHz的QPSK信号分别经双极化MZM调制,并经80 km SMF传输后,15 GHz的QPSK信号的传输性能表现更优,当光电检测器(PD)的输入功率高于-10.2 dBm时,其解调后的系统误码率(BER)低于3.8×10-3。系统结构简单,复杂度低,使用的电、光器件少,有效地降低了成本,在未来接入网中发挥了巨大的作用。

A vector system that uses a single laser source and a dual-polarized Mach-Zehnder modulator(MZM)to generate two channels of optical radio frequency signals at different frequencies is experimentally studied.Using the optical subcarrier multiplexing technology,two channels of quadrature phase shift keying(QPSK)signals can be carried by two optical subcarriers with different frequencies based on a modulator and an optical carrier.The polarization multiplexing technology is used to overcome crosstalk of optical signals with different frequencies,and the signals can be successfully transmitted over an 80-km-long single-mode fiber(SMF).In the experiment,15-and 30-GHz QPSK signals are modulated using a dual-polarized MZM based on a single sideband modulation format.After the 80-km SMF transmission,the 15-GHz QPSK signal transmission performance is better than that of the 30-GHz signal.When the input power of a photodetector(PD)is more than-10.2 dBm,the bit error rate(BER)of a system after demodulation is less than 3.8×10-3.The system has the advantages of simple structure,low complexity,and few electrical and optical devices,which effectively reduce cost and play a considerable role in the development of future access networks.