Polarization-multiplexed single-cavity dual-comb fiber laser and its running condition for ranging

We have firstly demonstrated a free-running, polarization-multiplexed, single-cavity dual-comb fiber laser with a simplified linear-cavity configuration. The repetition rate of the laser is around 86.3 MHz while its repetition rate difference can be tuned from 1.0 kHz to 1.8 kHz. Then, it is verified that the ranging precision by this dual-comb source can be optimized according to the carrier frequency of the beat interferogram signal. When the interferogram's carrier frequency is centered at 26 MHz by tuning the mode-locking state of the laser, a ranging precision of 392 nm is achieved with 67 ms averaging time. In further, we have found the radio frequency spectrum of the interferogram signal is hardly influenced by the change of the repetition rate difference, which leads to the consistency of the distance measurement. This result indicates dual-comb ranging by this compact single-cavity fiber laser is potentially robust to environmental disturbance and this laser source can be a good candidate for other dual-comb applications.