We present the theory and experimental results of a microwave photonic (MWP) filter based instantaneous frequency measurement system. A quantum dash mode-locked laser is used as an optical frequency comb source. With up to 41 flat comb lines and a real-time feedback loop for comb shaping, a set of MWP filters with linear frequency responses for either linear unit or dB unit are experimentally demonstrated. The maximum measurement frequency can be up to 20 GHz limited by the available test-and-measurement instruments. By using one MWP filter, the root-mean-square error is 51∼66 MHz, which can be improved to 42.2 MHz for linear unit, and 30.7 MHz for dB unit by using two MWP filters together.

中文翻译：

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基于量子冲模锁模激光器的瞬时测频系统

我们提出了基于微波光子（MWP）滤波器的瞬时频率测量系统的理论和实验结果。使用量子冲模锁模激光器作为光学频率梳源。通过多达 41 条扁平梳状线和用于梳状整形的实时反馈环路，实验演示了一组具有线性单位或 dB 单位的线性频率响应的 MWP 滤波器。受可用测试和测量仪器的限制，最大测量频率最高可达 20 GHz。使用一个 MWP 滤波器时，均方根误差为 51∼66 MHz，对于线性单元，可将其改善至 42.2 MHz；如果同时使用两个 MWP 滤波器，则可将 dB 单元改善至 30.7 MHz。