Signal-to-noise ratio improvement of photonic time-stretch coherent radar enabling high-sensitivity ultrabroad W-band operation.

The signal-to-noise ratio (SNR) of the photonic time-stretching receiver in the photonic time-stretch coherent radar (PTS-CR) system is theoretically analyzed. According to the analysis based on the erbium-doped fiber amplifier (EDFA) characteristic, it is found that the SNR is dominantly determined by the input optical power of the EDFA. With the improvement of the SNR of the photonic time-stretching receiver, the radar detection sensitivity is consequently enhanced. Furthermore, a PTS-CR system operating at W band with the ultrabroad bandwidth of 12 GHz is experimentally enabled, leading to the range resolution of ∼1.48  cm in dual-target detection.