Abstract For the direct modulation of a laser using frequency division multiplexed (FDM) channels, an iterative procedure is presented for power loading based on the signal-to-noise-and-distortion ratio. The power of nonlinear distortion arising from the modulation dynamics of the laser and dispersive transmission combined with direct detection is estimated using a two-tone test with the power being determined within the receiver bandwidth for each FDM channel. This allows the signal distortion to be isolated and provides a generic result that avoids having to specify the modulation format and execute system-level simulations. The noise arising from the receiver front-end is described by an equivalent thermal noise. The power loading procedure is tested numerically with 16 FDM channels using 8-ary phase shift keying (8-PSK), 16-ary quadrature amplitude modulation (16-QAM), or 32-QAM. The resulting FDM signal is transmitted over 30 km of standard single-mode fiber followed by direct detection. In the case of using 16-QAM, 60.8 Gb/s transmission is achieved, and despite the frequency-selective power fading, all channels perform under the target bit error ratio of 3.8 × 10−3. Moreover, the robustness of the power loading profile is evaluated by changing the transmission distance while using a profile optimized for a specific distance.

中文翻译：

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在 FDM 系统中为直接调制激光器的功率加载采用信噪比和失真比

摘要 对于使用频分复用(FDM) 信道的激光器直接调制，提出了一种基于信噪失真比的功率加载迭代程序。由激光器的调制动态和色散传输与直接检测相结合产生的非线性失真功率是使用双音测试估计的，功率在每个 FDM 信道的接收器带宽内确定。这允许隔离信号失真并提供通用结果，避免必须指定调制格式和执行系统级仿真。接收器前端产生的噪声用等效热噪声来描述。使用 8 进制相移键控 (8-PSK) 的 16 个 FDM 通道对功率加载程序进行了数值测试，16 进制正交幅度调制 (16-QAM) 或 32-QAM。产生的 FDM 信号通过 30 公里的标准单模光纤传输，然后进行直接检测。在使用 16-QAM 的情况下，实现了 60.8 Gb/s 传输，尽管存在频率选择性功率衰落，但所有信道都在 3.8 × 10−3 的目标误码率下运行。此外，通过改变传输距离同时使用针对特定距离优化的配置文件来评估功率负载配置文件的稳健性。