Fast‐Tuning and Narrow‐Linewidth Hybrid Laser for FMCW Ranging

Abstract Possessing a long coherent length, high repetition rate, and fast frequency‐sweeping laser sources with narrow linewidth is crucial components in coherent frequency‐modulated continuous‐wave (FMCW) light detection and ranging (LiDAR) systems. While these attributes are realized individually in standalone devices, the integration of these features into a single laser represents a significant advancement in the field. In this study, a hybrid integrated laser that achieves a linewidth of 9 kHz, a wide frequency‐modulation response extending up to 68 MHz, and a low chirp nonlinearity of 4.3 × 10 −6 at a repetition rate of 100 kHz is presented. The achievement of this performance is made possible through self‐injection locking of a DFB laser diode to a low‐loss Si 3 N 4 micro‐ring resonator on the dual‐layer Si 3 N 4 ‐Si platform. Through the application of a fast‐converging pre‐distortion algorithm and a driving signal with 150 mV amplitude, a linear FMCW signal with 1.05 GHz frequency excursion is generated. Exploiting the wideband FM response of the PIN phase shifter, a frequency‐agile FMCW light source engine capable of generating linear FMCW signals at repetition rates of up to 2 MHz is successfully developed. Leveraging these cutting‐edge capabilities, an FMCW LiDAR ranging system for target detection across varying distances, achieving a high ranging precision of 0.4 cm for targets at 6.2 m, is implemented. This innovative work not only demonstrates the feasibility of integrating multiple advanced functionalities into a single laser but also demonstrates the potential for enhancing the resolution and precision of FMCW LiDAR systems for a wide range of applications.