中文摘要：

为了降低ROF系统成本,增加传输距离,提高系统性能,提出了一种基于新型偏振稳定毫米波发生器的光载无线通信下行链路传输系统.与传统ROF系统相比,该系统利用保偏光纤光栅选频产生的两个偏振稳定激光信号拍频产生毫米波,易于实现并降低了功率噪声对系统的影响.仿真分析了该系统中环形激光器强度、谱线宽度、保偏光纤光栅反射谱特性对毫米波性能的影响;分析了系统中保偏光纤光栅的群时延、长度、色散,双波长激光信号脉冲包络宽度、啁啾系数对毫米波频率的影响.优化保偏光纤参数,差频产生60 GHz的毫米波信号,并分析该毫米波信号在ROF下行链路的传输性能,结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端,解调仍然得到很好的眼图,充分证明了本方案的优越性能.

英文摘要：

A radio-over-fiber（ROF） downlink system based on a new polarization-stable millimeter-wave generator is proposed to reduce costs, increase transmission distance and improve system performance. Compared with traditional system, the system uses two polarization-stable laser signals produced by selecting the frequency of the polarization maintaining fiber Bragg grating（PMFBG） to generate millimeter-wave by beating frequency. It is easy to be implemented and the influence of power noise on the system is reduced. The effects of laser power, linewidth and reflectance spectrum of PMFBG on the performance of millimeter-wave are analyzed; Simulation shows that the frequency of millimeter-wave is affected by the group delay, the length, the dispersion of the polarization-maintaining fiber（PMF） and the width, the chirp coefficient of laser＇s pulse profile. After optimizing parameters of PMF, millimeter-wave of 60GHz is generated, and the ROF downlink system is analyzed. The results of the study show that the eye dia- grams demodulated in the mobile station are excellent when the optical carrier which is modulated by the millimeter-wave serving as sub-carrier transmits over 80 kilometers from center station to base station. The excellent performance of the system is verified.