A photonics-based leakage cancellation and echo signal de-chirping approach for frequency-modulated continuous-wave radar systems is proposed based on a dual-drive Mach–Zehnder modulator (DD-MZM). The de-chirp reference signal and the leakage cancellation reference signal are combined and applied to the upper arm of the DD-MZM, while the received signal, including the leakage signal and echo signals, is applied to the lower arm of the DD-MZM. When the amplitudes and delays of the leakage cancellation reference signal and the leakage signal are precisely matched, the leakage signal is canceled in the optical domain. The de-chirped signal is obtained after the leakage-free optical signal is detected in a photodetector. An experiment is performed. The cancellation depth of the leakage signal after de-chirping is around 23 dB when the center frequency and bandwidth of the linearly frequency-modulated signal are 11.5 and 2 GHz, respectively. When the leakage cancellation is not employed, the leakage will seriously affect the imaging results and distance measurement accuracy. When the leakage cancellation is enabled, the imaging results of multiple targets can be clearly distinguished, the distance measurement error of a moving target is significantly reduced to less than 10 cm, and a dynamic range increase of 21 dB is achieved.

中文翻译：

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基于光子学的调频连续波雷达系统去啁啾和泄漏消除

基于双驱动马赫-曾德尔调制器（DD-MZM），提出了一种基于光子学的用于调频连续波雷达系统的泄漏消除和回波信号去啁啾方法。去啁啾参考信号和泄漏消除参考信号被组合并施加到DD-MZM的上臂，而接收到的信号，包括泄漏信号和回波信号，被施加到DD-MZM的下臂. 当泄漏抵消参考信号和泄漏信号的幅度和延迟精确匹配时，泄漏信号在光域被抵消。去啁啾信号是在光电探测器中检测到无泄漏光信号后获得的。进行了一个实验。当线性调频信号的中心频率和带宽分别为 11.5 和 2 GHz 时，去啁啾后泄漏信号的消除深度约为 23 dB。当不采用泄漏消除时，泄漏会严重影响成像结果和测距精度。开启泄漏消除后，可以清晰地区分多个目标的成像结果，移动目标的测距误差显着降低到10 cm以下，动态范围提升21 dB。