Low Error and Broadband Microwave Frequency Measurement Using a Silicon Mach–Zehnder Interferometer Coupled Ring Array

The integrated photonic technologies benefit from an improved frequency measurement range with compact size relative to the radio frequency counterparts. Nevertheless, the measurement methods are generally limited by a basic trade-off between the measurement range and accuracy. In this work, we break the above limitations and trade-off based on a Mach–Zehnder interferometer (MZI) coupled ring array and a two-step measurement method. The experimental results show that a wide measurement range of 40 GHz and an ultra-low error of 9 MHz could be obtained. Moreover, owing to the ring flexibly tunable bandwidth and resonant wavelength, the measurement range and accuracy could be significantly adjusted. Another frequency measurement range of 20 GHz with a lower error of 4 MHz is also demonstrated. To the best of our knowledge, among the silicon-based measurement schemes, it is a record estimation error with such a wide range. With the dominant advantages of CMOS-compatibility, a broad measurement range, ultra-low estimation errors and adjustable measurement performance, the proposed microwave measurement scheme has many important applications in on-chip microwave systems.