Phase-Multiplied Interferometry via Cavity Dynamics for Resolution-Enhanced Coherent Ranging

Coherent light detection and ranging (LiDAR) has emerged as an indispensable tool in autonomous systems, offering exceptional precision and ambient-light immunity. Recently, applications spanning from scientific research to advanced manufacturing demand resolution beyond current capabilities, which face a fundamental trade-off between improved performance and system complexity. Here, we break through the intrinsic limitation and demonstrate a cavity-dynamics-enabled approach that spontaneously enhances ranging resolution through phase multiplication. By injecting target-scattered light into the optical resonator, the laser's operating frequency undergoes periodic modulation, generating interference harmonics that multiply phase sensitivity. Experimentally, we observe the excitation of up to 13th-order harmonic and effective phase multiplication without physical modulation extensions, and achieve over 10 times resolution enhancement for ranging. Owing to the inherent phase correlation between the fundamental and harmonic waves, the phase noise is effectively controlled, thus enabling high-precision ranging on the order of tens of micrometers. The system concurrently leverages laser feedback sensitivity, achieving significant signal-to-noise ratio (SNR) improvement. With its enhanced resolution, low photon consumption, and low-cost implementation, this technology establishes a foundation for next-generation perception systems.