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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.
In order to reduce the cost of ROF system, increase the transmission distance and improve the performance of the system, a downlink transmission system based on the new polarization stabilized millimeter-wave generator is proposed. Compared with the traditional ROF system, The two polarization stable laser signals generated by grating frequency selection beat to produce millimeter wave, which is easy to implement and reduces the impact of power noise on the system. The simulation analysis of the ring laser intensity, spectral width, the polarization characteristics of the polarization maintaining fiber grating On the performance of millimeter-wave. The influence of group delay, length, dispersion, pulse envelope width and chirp coefficient on the millimeter-wave frequency of polarization-maintaining fiber grating in the system is analyzed. Frequency generated 60 GHz millimeter wave signal and analyze the transmission performance of the millimeter wave signal in the ROF downlink, the results show that the millimeter wave as a subcarrier modulated onto the light wave transmitted from the central station 80 km to the base station via the antenna to the user End, demodulation still get a good eye diagram, fully proved the superior performance of the program.