Frequency upconversion of multiple RF signals using optical carrier suppression for radio over fiber downlinks.
Frequency upconversion of multiple RF signals using optical carrier suppression for radio over fiber downlinks.
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DOI：
10.1364/oe.15.016737
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发表时间：
2007-12
期刊：
影响因子：
3.8
通讯作者：
Zhenbo Xu;Xiupu Zhang;Jianjun Yu
中科院分区：
文献类型：
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作者：
Zhenbo Xu;Xiupu Zhang;Jianjun Yu
我们提出并分析了一种利用光载波抑制的光载波传输两个射频信号的技术。光载波抑制和信号调制均采用单光马赫-曾德尔调制器，射频信号的频率转换也采用光载波抑制调制。这项工作表明，与光载波通过光载波抑制传输单个射频信号的情况相反，更强的光载波抑制可以改善上转换的射频信号，而对于由于非线性失真而传输两个射频信号的光载波，由于使用更弱的光载波抑制可以减少非线性失真，因此更弱的光载波抑制是首选的。研究发现，对于上变频到20ghz及以上的射频信号，光载波抑制比的可用范围为10 ~ 18db，最佳光载波抑制比在10db左右。我们用实验验证了这个概念和分析。在实验中，我们使用6 GHz和18 GHz的两个rf传输两个750 Mb/s的信号。该实验首次证明了利用光载波抑制一个光载波可以传输两个射频信号，并表明了上变频射频信号受到非线性失真的影响，特别是对于12 GHz的上变频射频信号，即较低频率的射频信号。
We propose and analyze a technique of an optical carrier transmitting two RF signals using optical carrier suppression. A single optical Mach-Zehnder modulator is used for both optical carrier suppression and signal modulation, and optical carrier suppression modulation is also used for frequency conversion of RF signals. This work shows that in contrary to the case of an optical carrier transmitting a single RF signal with optical carrier suppression where stronger optical carrier suppression improves the upconverted RF signal, weaker optical carrier suppression is preferred for an optical carrier transmitting two RF signals due to nonlinear distortion because the nonlinear distortion is reduced by using weaker optical carrier suppression. We find that the usable range of optical carrier suppression ratio is from 10 to 18 dB for RF signal upconverted to 20 GHz and beyond, and the best optical carrier suppression ratio is around 10 dB. We verify the concept and analysis with experiment. In experiment, we used two RFs at 6 and 18 GHz transmitting two 750 Mb/s signals. The experiment for the first time demonstrated that an optical carrier can transmit two RF signals using optical carrier suppression and showed that upconverted RF signals are degraded by nonlinear distortion, particularly for upconverted RF signal at 12 GHz, i.e. the RF signal at the lower frequency.