Experimental Study on Variation of Signal Amplitude in Radio-Over-Fiber Transmission Induced by Harmonics of Modulation Sidebands Through Fiber Dispersion
Experimental Study on Variation of Signal Amplitude in Radio-Over-Fiber Transmission Induced by Harmonics of Modulation Sidebands Through Fiber Dispersion
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光纤色散调制边带谐波引起光纤无线电传输信号幅度变化的实验研究
DOI：
10.1109/jlt.2014.2330612
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and Satoshi Ebisawa
中科院分区：
文献类型：
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作者：
Joji Maeda;Kohei Kimura;and Satoshi Ebisawa
实验研究了光纤色散对微波信号在光纤上无线传输的影响。在先前的论文（J. Lightwave Technol.，第30卷，第2625-2632，2012年8月），作者分析预测，由光调制器的非线性响应生成的边带的谐波将有助于信号幅度的循环变化，而不是由色散引起的衰落。为了证实这一预测，我们建立了一个RoF链路，传输16正交幅度调制微波信号，我们观察到星座图的变化。实验分别针对光双边带（OSSB）信号和光单边带加载波（OSSB+C）信号进行。在ODSB的情况下，当信号沿光纤向下传播时，星座图中的外部符号稍微向外移动。如果我们通过使用光学滤波器消除谐波边带，则运动是相反的;这可能是由于LN调制器中的残余啁啾。在OSSB+C的情况下，我们观察到类似的运动，但也有轻微的相位旋转，这取决于符号的振幅。这些观察结果在性质上与我们的预测一致。
Effects of fiber dispersion on the radio-over-fiber (RoF) transmission of a microwave signal are experimentally demonstrated when deep optical modulation is employed. In a previous paper (J. Lightwave Technol., vol. 30, pp. 2625–2632, Aug. 2012), the authors analytically predicted that harmonics of sidebands generated by the nonlinear response of optical modulators would contribute to the cyclic variation of the signal amplitude other than by dispersion-induced fading. To confirm this prediction, we set up an RoF link that transmitted a 16-quadrature amplitude modulation microwave signal, and we observed changes in the constellation map. Experiments were conducted both for optical double-sideband (ODSB) signals and optical single-sideband plus carrier (OSSB+C) signals. In the ODSB case, outer symbols in the constellation map moved slightly outwards as the signal propagated down the fiber. If we eliminated the harmonic sidebands by using an optical filter, the movement was reversed; this was probably due to the residual chirp in the LN modulator. In the OSSB+C case, we observed a similar movement but also a slight phase rotation that depended on the amplitude of the symbol. These observations qualitatively agree with our predictions.