Ultra-Broadband Microwave Frequency Measurement Based on Two-Dimensional Information Mapping via Transient Stimulated Brillouin Scattering of Chirped Optical Pulse Sequences

This paper proposes a system based on the chirped optical pulse sequence (COPS)-stimulated Brillouin scattering (SBS) effect that utilizes two-dimensional information mapping to realize instantaneous, high-precision and ultra-broadband microwave frequency measurement (MFM). In the proposed MFM system, the unknown signals of different frequencies are frequency-selected by the SBS effect on the COPS to obtain time-dimensional information corresponding to the frequency. The differential response of the optical band-pass filter at different wavelengths is then used to acquire the amplitude-dimensional information corresponding to the frequency. Simultaneous mapping of these dimensions allows for high-precision measurement of the signal under test. The proposed system's single-tone, dual-tone and quad-tone microwave frequency measurements are validated experimentally, and the proposed system exhibits a minimum measurement time of 100 ns with a frequency measurement accuracy of less than 1 MHz and an instantaneous bandwidth exceeding 20 GHz.