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    • 摘要: 为了更好地利用光纤带宽并提升RoF系统的通信能力,将光子矢量调制和光生毫米波技术结合,提出了一种基于偏振复用(PDM)的18倍频16正交振幅调制(QAM)毫米波生成方案。该系统包含倍频和矢量调制两个并联模块。在倍频模块利用两个双平行马赫曾德尔调制器(DP-MZM)和一个光相移器生成±6阶光边带,经过半导体光放大器后激发四波混频效应,再经过滤波处理得到18阶边带。在矢量调制模块,利用八路10 Gbit/s的二进制NRZ信号驱动DP-MZM,结合偏振复用技术,实现了两个正交偏振方向上的16QAM的光域调制。将PDM-16QAM信号与18阶光边带耦合,经光电探测器拍频后生成了18倍频PDM-16QAM信号。仿真分析表明,当光电探测器接收功率为−25 dBm时,系统信噪比大于20.5 dB的矢量信号经过30 km的单模光纤传输后,系统性能良好,当SOA注入电流和激光线宽存在一定范围波动时,系统误码率仍可低于3.8×10−3

       

      Abstract: To better utilize the optical fiber bandwidth and enhance the communication capability of the RoF system, this paper combines photonic vector modulation and optical millimeter-wave generation techniques, proposing an 18-fold frequency 16 quadrature amplitude modulation (QAM) millimeter-wave generation scheme based on polarization division multiplexing (PDM). The system consists of two parallel modules: frequency doubling and vector modulation. In the frequency doubling module, two dual-parallel Mach-Zehnder modulators (DP-MZM) and an optical phase shifter are used to generate the ±6th-order optical sidebands. After passing through a semiconductor optical amplifier (SOA), four-wave mixing effects are induced, and the 18th-order sidebands are obtained through filtering. In the vector modulation module, eight 10 Gbit/s binary NRZ signals drive the DP-MZM, and polarization multiplexing technology is applied to implement 16QAM optical domain modulation on two orthogonal polarization directions. The PDM-16QAM signal is coupled with the 18th-order optical sidebands and, after photodetection, an 18-fold frequency PDM-16QAM signal is generated. Simulation analysis shows that when the photodetector's received power is −25 dBm, the signal-to-noise ratio (SNR) of the system is greater than 20.5 dB, and after 30 km transmission through single-mode optical fiber, the system performance remains good. Even when there are fluctuations in the SOA injection current and laser linewidth within a certain range, the bit error rate (BER) of the system remains below 3.8×10−3.