【作者】 高嵩；

【导师】 裴丽；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2013， 博士

【摘要】 ROF (Radio over Fiber)系统结合了光纤通信和无线通信的优点,是微波光子学应用的一个重要体现,在未来宽带移动通信系统中具有广阔的应用前景。本论文结合国家自然科学基金及教育部博士点基金项目,对ROF系统中毫米波生成及传输的一些关键技术进行了深入的理论分析、仿真和实验研究,获得主要创新成果如下：1.根据激光器噪声和光纤链路中简化的加性噪声理论模型,结合随机信号传输相关知识,分析了色散对光载毫米波生成和解调的影响。借助统计学的相关知识分析了偏振失谐对光载毫米波生成和传输的影响,利用自制的保偏光纤光栅(Polarization Maintaining Fiber Bragg Grating,PMFBG)搭建了双波长激光器,实验生成频率22GHz左右的微波信号,验证了偏振失谐对ROF系统中微波信号生成的影响。2.提出一种并联马赫曾德尔调制器(Mach-Zehnder Modulator, MZM)结构,可以理论实现8倍频毫米波的生成。基于该结构提出一种双向ROF系统,该系统可在为下行链路提供4倍频毫米波信号的同时为上行链路提供降频信号,实现100%的频率利用率。该方案可应用于未来宽带移动通信系统中,有效的降低系统成本。3.利用三角波代替正弦波调制MZM,仿真得到了信噪比20dB以上的10倍频毫米波生成,并将该方法应用到60GHz-ROF系统中。结果表明在相同的调制条件下,利用三角波扫频可有效提高光学倍频法的倍频因子,得到高频率的毫米波信号。4.利用自制的光纤光栅型声光滤波器进行边带抑制,实现了ROF系统中双边带信号向单边带信号的转换,可将系统边载比从9.73dB提高到2.9dB,接收灵敏度从-23.43dBm提高到-31.18dBm。该方案有效减小了光纤色散的影响,为提高ROF系统性能提供了一种简便、低成本的解决方法。5.实验制备了高性能的PMFBG,基于制备的PMFBG分别建立了倍频因子高达16的光学倍频法和可调谐ROF系统的理论模型,根据理论模型对两者进行了工作原理分析,并最终评估了两种方法的系统性能,证实了其可行性。更多还原

【Abstract】 As one of the most important applications of microwave photonic, ROF (Radio over Fiber) system, which combines the advantages of optical communication and wireless communication, is a good candidate for broadband mobile communication. Under the supports of the National Nature Science Foundation of China and the Ph.D. Programs Foundation of Ministry of Education of China, some key technologies for millimeter-wave generation and transmission is analized and verified by simulation or experiment in this thesis. And the main achievements of this thesis are listed as follows:1. According to the theoretical model of laser noise and simplified additive noise, the impact of millimeter-wave (mm-wave) generation and demodulation caused by fiber dispersion is analysed by using the stochastic signal transmission theory. The impact of mm-wave generation and demodulation caused by polarization mismatch is also discussed. A dual-wave laser incorporating a homemade polarization maintaining fiber Bragg grating (PMFBG) is used to generate microwave signals with frequencies around22GHz. The experimental results verify our theoretical analysis.2. A parallel structure of Mach-Zehnder Modulator (MZM), which can be used for generating mm-wave via frequency octupling, is proposed. Based on the proposed structure, a bidirectional ROF system, which is capable of generating and transmitting frequency quadrupling mm-wave signal for downlink and providing down conversion frequency components for uplink, is investigated. In the system, the rate of spectrum usage efficiency as high as100%can be achieved. The study results of the proposed scheme demonstrate that it can offer realistic solutions to support future broadband wireless systems.3. A scheme based on a MZM which is driven by triangular wave instead of sine-wave is theoretically proposed. With signal to noise ratio higher than20dB, an mm-wave with multiplication factor (MF) of10is generated. Based on the60GHz mm-wave generation, a ROF downlink transmission performance is evaluated. The result verifies that the scheme is capable of improving the multiplication factor in optical frequency multiplication (OFM).4. An optical single sideband modulation ROF system, by using a homemade acousto-optic filter, is proposed and demonstrated. The carrier to sideband ration is reduced from9.73to2.9dB, and the receiving sensitivity improved from-23.43to-31.18dBm at BER of10-9with30km long SMF. This scheme effectively reduces the influence of the fiber dispersion, and provides a simple, low-cost solution for improving the ROF system performance.5. An OFM with MF as high as16and a tunable ROF system are proposed. The theoretical models of the OFM and ROF system are built by using homemade PMFBGs. Based on the models, the principles are analysed and these two schemes are verified by evaluating the system performances.更多还原