Photonic-crystal microresonator-based LiDAR engine

Self-injection-locked (SIL) narrow-linewidth lasers based on high-Q microresonators are promising sources for frequency-modulated continuous-wave (FMCW) LiDAR, but the SIL mechanism, as well as its key characteristics, such as the frequency sweep range and the noise performance, are often determined by uncontrolled backscattering in the resonator. Here, we investigate a tunable SIL laser based on a corrugated photonic-crystal (PhC) microresonator in which the feedback strength is set by design. Numerical and experimental results show that stronger SIL feedback expands the sweep range accessible through resonator modulation while also impacting the phase-noise and linewidth during sweeping, revealing a trade-off between frequency tunability and noise performance. Using CMOS-compatible microheater tuning (sub-1 V driving voltage), we demonstrate linearized up- and down-chirps with 224 THz/s over approximately 3 GHz and, in a proof-of-concept ranging experiment, measure a 10 m fiber length with a standard deviation below 3 mm. These results establish PhC microresonators with engineered SIL feedback as robust, compact, CMOS-compatible LiDAR engines.