Integrated polarization-diverse FMCW LiDAR with real-time CFAR for high-reliability long-range detection

Frequency modulated continuous wave (FMCW) LiDAR offers strong interference immunity, eye safety, and simultaneous distance-velocity measurement. However, long-range and low-reflectivity detection is often limited by polarization fading, reduced return power, bandwidth constraints, and system noise. This work presents a silicon-photonic polarization-diverse coherent receiver that enables both polarization states of the return signal to participate in coherent detection, reducing polarization-induced fading. A pipeline real-time constant false-alarm rate (CFAR) is further incorporated to robustly identify beat-frequency peaks under long-range and high-frequency-attenuated conditions. Experiments show that for a 200 m target with 10% reflectivity, the detection probability increases from 43.5% to 97% after applying CFAR and polarization-diverse detection. The system achieves real-time 4D imaging at 100,000 points per second, demonstrating improved detection reliability for integrated FMCW LiDAR.