Absolute distance measurement with a large non-ambiguity range based on a stable polarization-multiplexed dual-comb fiber laser

We proposed an absolute distance measurement method with a large non-ambiguity range based on a polarization-multiplexed dual-comb fiber laser. By fully exploiting the intracavity linear loss based gain profile tilting and residual birefringence, polarization-multiplexed dual-comb pulses with tunable repetition rate difference and overlapping spectra in the 1530-nm gain region are obtained. The repetition frequency difference could be continuously tuned from ~89 to ~194 Hz. The alternative sampling under different repetition rate difference is experimentally verified to be effective approach to extend the non-ambiguity range in the single-cavity dual-comb ranging. The non-ambiguity range could reach thousands of kilometer while the precision could reach at least on the order of hundreds of micrometers. These results indicate a simple and intriguing route with a free-running laser source to obtain ranging with large non-ambiguity range, showing high potential in the applications such as satellite formation flying, large-scale 3D surface morphology measurement and so on.