A Gap‐Free Real‐Time Broadband Spectrum Analyzer by Overlapping Optical Short‐Time Fourier Transform

Abstract Continuous real‐time analysis of the microwave spectrum is crucial for observing and analyzing high‐speed random events and short‐duration transient events. However, most current schemes analyze the spectrum in real‐time with gaps, which inevitably leads to the loss of some critical information. A gap‐free real‐time microwave spectrum analyzer based on temporal convolution is demonstrated experimentally. By leveraging the temporal overlapping of stretched pulses, the analyzer achieves a high frame rate of 233 MHz, a frequency resolution of ≈500 MHz, an instantaneous bandwidth (dual sidebands) of nearly 130 GHz, a 100% signal capture ratio, and a measurement accuracy better than 20 MHz. Owing to the exemplary system performance, the real‐time dynamic frequency identification for different types of microwave signals covering the S‐band to Q‐band is demonstrated, and the frequency can be accurately identified at any given time. Furthermore, the real‐time capturing of transients is also demonstrated continuously. The high‐performance analyzer can open a new horizon for real‐time analysis and processing of high‐speed time‐domain waveforms in communication, imaging, and sensing applications.