Dual-comb absolute distance measurement based on a dual-wavelength passively mode-locked laser

A new absolute distance measurement system is demonstrated in this paper, which is based on a dual-wavelength passive mode-locked fiber laser. By controlling the intracavity loss and spectral filtering, the cavity mode-locked by a single-wall carbon nanotube saturable absorber is able to generate two pulse trains at slightly different repetition rates simultaneously with high mutual coherence. Comparisons with the commercial interferometers located on the 80-m large-scale dimensional standard show a combined measurement uncertainty of 6 μ m + 1 × 10^-7L (k = 2), in an averaging time of 1 s. Our compact dual-comb system provides a low-cost way for ranging, with continuous range, rapid measurement, and high resolution.