Ultra-linear FMCW laser based on time-frequency self-injection locking

Frequency-modulated continuous-wave (FMCW) light sources are essential components for coherent light detection and ranging (LiDAR), which is ubiquitously utilized in autonomous driving, industrial monitoring, and geological remote sensing. Traditional FMCW LiDAR systems often face challenges in achieving high frequency-sweep linearity and large excursion, which are critical for accurate distance and velocity measurements. Here, we propose a self-injection locked laser with frequency-shifted feedback to generate ultra-linear and wideband FMCW light. A record-low relative frequency nonlinearity of 6.4×10 −7 is achieved when the frequency excursion is 100 GHz and the repetition frequency is 1 kHz. In the LiDAR test, a range resolution of 1.6 mm and a velocity accuracy of 3 mm/s at 300 m distance are demonstrated, and those of 8.1 mm and 6 mm/s at 1 km distance are also obtained. The reported FMCW light source provides not only enhanced performance in coherent LiDAR, but also utilization potential in various high-precision measurement scenarios.