A photonics-based scheme is proposed to generate wideband linear frequency modulation pulses with broadly tunable carrier frequencies for coherent radars. The approach integrates the concept of the microwave-photonic multiplication and coherent beating to enable reconfiguration of the bandwidth and carrier frequency of the generated pulses. The phase fluctuation between two beating arms is suppressed by a stabilization technique based on an optical phase-locked loop to maintain the pulse-to-pulse phase coherence. Further, we also demonstrate a coherent radar system, including the generation, wireless transmission and detection of the radar echo signal in the Ka-band. The coherent integration of several echo signals is achieved. About 8 dB of signal-to-noise ratio improvement is obtained with every ten-fold of integration times. The range resolution of the radar system is $\sim 3.75\mathrm{cm}$, which is close to the theoretical prediction.

中文翻译：

---

基于光子学的相干宽带线性调频脉冲信号生成

提出了一种基于光子学的方案，以产生相干雷达具有宽可调载频的宽带线性频率调制脉冲。该方法整合了微波光子倍增和相干跳动的概念，以实现对所产生脉冲的带宽和载波频率的重新配置。通过基于光学锁相环的稳定技术可以抑制两个拍臂之间的相位波动，以保持脉冲到脉冲的相位相干性。此外，我们还演示了一种相干雷达系统，包括在Ka波段中雷达回波信号的生成，无线传输和检测。实现了几个回波信号的相干积分。每十倍的积分时间可获得约8 dB的信噪比改善。$〜3.75\mathrm{厘米}$，这接近理论上的预测。