Compact low-noise dual microcombs for high-precision ranging and spectroscopy applications

Microresonator-based dual-comb technology has emerged as a transformative tool for precision measurements, driving advances in ultrafast distance measurement, high-resolution spectroscopy, and optical coherence tomography. In dual-comb heterodyne systems, measurements critically depend on the long-term stability of the combs—an inherent challenge for free-running microcombs due to their susceptibility to phase noise and frequency drift. While active stabilization schemes can enforce comb synchronization, their reliance on external feedback mechanisms inevitably reintroduces the very complexity these integrated systems aim to eliminate—creating a paradoxical barrier to practical applications, particularly in compact, field-deployable platforms. To address these challenges, we present a low-noise Kerr frequency comb device integrated within a coin-sized, electrically driven butterfly package. By leveraging self-injection locking to a high-Q, large-mode-volume fiber Fabry–Perot resonator, we achieve an unprecedented reduction in phase noise: reaching −129dBc/Hz at 10 kHz, −142dBc/Hz at 100 kHz, and −158dBc/Hz at the noise floor, approaching the quantum noise limit. This compact device exhibits key practical advantages, including low-power consumption, long-term operational stability, and turnkey functionality. Crucially, the high coherence of the generated comb enables a locking-free dual-comb system capable of achieving single-micron-level ranging accuracy and spectroscopic precision with errors below 1%—performance comparable to fully stabilized dual-mode-locked laser systems. Our work demonstrates Kerr combs with a low fundamental noise limit enabled by a novel platform structure, to our knowledge, and establishes a new paradigm for high-performance, compact frequency comb sources. These advances pave the way for the widespread adoption of Kerr comb technology in real-world applications beyond laboratory settings, spanning precision metrology, communications, and remote sensing.