Instantaneous Microwave Frequency Measurement Based on Phase-Modulated Links With Interferometric Detection

A novel instantaneous frequency measurement scheme based on phase-modulated links with interferometric detection is experimentally demonstrated. Due to the different time delays of the Mach-Zehnder interferometers (MZIs), the free spectral ranges of the two channels transmission responses would also be different. By comparing them, we establish the amplitude comparison function (ACF). Through the unique relationship between the ACF and the microwave frequency, the microwave frequency to be measured can be estimated easily. The proof-of-concept experimental results show that the measurement errors can be kept within 0.2 GHz over a frequency range of 3.5-10 GHz. In addition, the measurement range can be adjusted by tuning the time delays of the MZIs.