Precise Distance Measurement by Multi-Wavelength Interferometry Using a Soliton Microcomb

In this work, we present a method for precise distance measurement through microcomb-based multi-wavelength interferometry. The high repetition frequency of the microcomb results in a non-ambiguity range confined to the millimeter or centimeter scale. To address this limitation, we leverage the microwave signal inherently carried by the microcomb to significantly extend the non-ambiguity range. Initial coarse distance measurements are obtained via the phases of the microwave signal. These measurements are subsequently refined using multi-wavelength interferometry, with the microcomb serving as the direct signal source. Experimental results indicate that the comparison with the reference distance meter can be within 44 nm. The Allan deviation can reach 43 nm at 4 s, and 8.6 nm at 100 s averaging time. Our system is able to provide a ranging method with nanometric precision and extremely large non-ambiguity range.