一种改善实时性的光辅助微波频率测量方法的研究

Study on Photo-Assisted Microwave Frequency Measurement Method with Improved Real-Time Performance

针对分段光辅助微波频率测量实时性不足的缺陷，提出一种新的改善实时性的光辅助微波频率测量方法。被测微波信号从上下两支路通过双平行马赫一曾德尔调制器（DPMZM）同时对两路不同波长激光进行调制，调制输出激光经过单模光纤、光电转换器还原出微波信号。设置上下支路DPMZM的相位偏置电压，使上支路频率测量范围大，下支路频率测量范围小，在电域分两步计算处理得到被测微波信号频率。该方法避免了装置的调整及重新校准，从而实现更好的测量实时性。实验结果显示，实验装置在4．3—18．7GHz的频率范围测量时间小于70μs、测量误差±0．4GHz。

This paper proposes a novel photo-assisted microwave frequency measurement strategy with proved real-time performance to tackle with the defect of low real-time performance in conventional segmented photon- assisted microwave frequency measurement. The microwave signal to be measured passes through the upper and lower branches of dual-parallel Mach-Zehnder modulator （DPMZM） and simultaneously modulates the two branches of laser with different wavelengths. The modulated output laser of the two branches then demodulates the signal to be measured by single-mode fiber dispersion and photoelectric converter. Different bias voltages are provided to the two branches of DPMZM so that the upper branch measurement range is large, and the lower branch measurement range is small, respectively. Therefore, the frequency of the microwave signal to be measured can be obtained by a two-step calculating process in electric domain. This method eliminates the need of adjustment and recalibration of the device and thus achieves better real-time performance. Experimental results show a measurement time of less than 70 μs with resolution of ＋0.4 GHz in rang of 4.3-18.7 GHz.