Photonic Generation of 30 GHz Bandwidth Stepped-Frequency Signals for Radar Applications

Wideband microwave signals with high time-frequency linearity for high-resolution radar applications can be optically generated using high-speed electronic waveform generators. Frequency-shifting modulation in an optical cavity provides attractive approach to generate broadband reduced complexity requiring only MHz-level electronics. However, the in-loop signal instability and inter-pulse interference usually cause amplitude fluctuations, leading limited signal-to-noise ratio bandwidth. Here, we overcome these challenges demonstrate, first time, photonic generation of 30-GHz-wide stepped-frequency (SF) 100 MHz frequency steps defined by electrical oscillator. We achieved this performance mitigating polarization scrambling a polarization-maintaining high-extinction switch. This allows stable consecutive acousto-optic frequency-shifting that significantly improves ratio. While achieving bandwidth surpassing state-of-the-art demonstrations based on wideband electronics, our alleviates necessity generators or tunable lasers. To exemplify utility, systematically evaluate quality show its imaging compared those