Three-band triangular linearly frequency-modulated continuous-wave microwave photonic radar based on the gain-switched DFB laser

A compact three-band symmetrical triangular linearly frequency-modulated (TLFM) continuous-wave radar based on the gain-switched DFB laser is proposed in this paper. By introducing the low central-frequency TLFM signal with high-power to modulate the DFB laser, the DFB laser would enter into the gain-switching state and a coherent and stable three-band broadband TLFM signals (S-/C-/X-band) with a bandwidth of 0.4*N GHz ( N = 1, 2, 3) would be generated after the photodetector. Based on this condition, one three-band TLFM continuous-wave radar system can be realized. The system does not require an external modulator in multi-band generation, and uses a single-channel transceiver module to achieve simultaneous transmission and echo dechirp processing of multi-band radar, which greatly reduces the deployment difficulty of the multi-band radar system, so the cost, size, weight and other characteristics of the system are expected to be reduced. In the current proof-of-concept experiment, the range resolution of the three-band TLFM signal can reach 13.8 cm, compared with the single-band TLFM signal which cannot distinguish the targets.