A photonic approach to broadband microwave frequency measurement

A novel photonic approach to microwave frequency measurement based on interference effect of microwave signals is proposed. In the simple measurement system, an unknown microwave signal is modulated simultaneously on two optical carriers with different wavelengths through a Mach-Zehnder modulator (MZM). The optical output from the MZM propagates in a dispersive medium, leading to different phase shifts. By scanning the wavelength of one optical carrier, the frequency of the microwave signal can be obtained directly through analyzing the interference intensity of the microwave signal from the photodetector. The validity of the proposed approach is demonstrated experimentally by obtaining the unknown microwave frequency from 1 to 15GHz.