提出了一种基于可调光延迟线的光子学微波频率测量方法。经同一微波信号调制的两个不同波长光载波在经过一段可调色散介质传输后，解调输出两路具有不同相位的微波信号，得到的相干微波功率随着色散量的改变出现周期性变化，由此周期可得到输入微波频率值。采用由8个磁光开关和1.6 km单模光纤构成的7-bit光纤延迟线实现色散量的调节。实验结果表明，在1～20 GHz范围内，测量精度达±40 MHz以内。系统的最小可测功率可达－20 dBm，测量动态范围达到了45 dB。

A photonic approach for microwave frequency measurement is proposed. A phase difference of the two microwave signals carried on two optical wavelengths is induced by a tunable dispersion medium. The interference microwave power is tuned periodically by changing dispersion value. The frequency of the microwave signal can be extracted from the period. In the proposed approach, a 7-bit optic delay line composed by 8 magneto-optical switches and 1.6 km single-mode fiber (SMF) is utilized as the tunable dispersion medium. The measurement accuracy remains within ±40 MHz over a range of 1～20 GHz. The minimum measureable power can reach to -20 dBm and the dynamic range is 45 dB.