We investigated the FM noise characteristics of a distributed feedback laser under optical negative feedback from a Fabry–Perot optical filter using delayed self-homodyne coherent detection with a high-frequency range of 1 × 10 5 –2 × 10 10 Hz. The measured FM noise power spectral densities of the laser under the optical negative feedback strongly depend on the modulation responses of the laser. These results were reproduced in calculations based on a transfer function model. Our findings suggest that wide bandwidth semiconductor lasers are suitable for reducing FM noise in a wide frequency range and enhancing the feedback loop gain (FM noise reduction ratio) under a sufficient phase margin in optical negative feedback.

中文翻译：

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光学负反馈下调制带宽在窄谱线宽半导体激光器中的作用

我们研究了法布里-珀罗光学滤波器在光学负反馈下使用延迟自同调相干检测和1×10 5 –2×10 10 Hz高频范围的光负反馈下的FM噪声特性。在光学负反馈下测得的激光的FM噪声功率谱密度在很大程度上取决于激光的调制响应。这些结果在基于传递函数模型的计算中得以重现。我们的发现表明，宽带半导体激光器适用于在较宽的频率范围内降低FM噪声，并在光学负反馈具有足够的相位裕度的情况下提高反馈环路增益（FM噪声降低比）。