Frequency Agile Dual-Chirp Microwave Waveform Generation with MZM

Linear chirped waveforms are widely used in modern radars to enhance the range resolution due to high pulse compression capability [1]. However, the single linearly chirped waveforms have a knife edge ambiguity function, which reduces the range-Doppler resolution. Dual-linear chirp microwave waveforms have low range-Doppler coupling, enhancing range-Doppler resolution. Photonic dual-chirp waveform generation has been demonstrated using dual parallel Mach Zehnder modulators (DPMZM) [2], and dual-drive Mach Zehnder modulator (DDMZM) [3]. However, these techniques require complex modulators and precise DC bias control to generate a dual-linear chirped waveform, limiting system robustness for environmental challenges. Some photonic techniques use optical injection techniques for generating dual-chirps [4], however it comes with challenges related to system complexity, where precise control of master and slave laser is required. In this paper, we present a straightforward method to generate a frequency agile dual-chirp waveform using a single MZM modulator and a tunable reference laser, where the center frequency is tuned by varying the reference laser frequency. A frequency agile dual-chirp wavefrom generator from 5 GHz to 20 GHz has been experimentally demonstrated.