Tunable dual-comb spectroscopy in a single asynchronous vector soliton fiber laser

Dual-comb spectroscopy is an advanced method for high-resolution and rapid measurement. Tunable dual combs are beneficial for diverse spectroscopy applications. For single-cavity dual combs, wide tunability is difficult to accomplish due to their completely identical physical paths. In this work, we investigate tunable dual-comb spectroscopy in a single asynchronous vector soliton fiber laser, overcoming the tuning difficulty by carefully designing the multiplexing mechanism. The tuning range is from 198 to 3940 Hz of repetition frequency difference and 8.7 MHz of carrier-envelope-offset frequency difference, where we report the widest repetition-frequency-difference tuning among such kinds of dual combs. When tuning the carrier-envelope-offset frequency difference to move the down-conversion RF spectrum away from half of the repetition frequency, characteristics of asynchronous solitons had noticeable changes, causing a decrease in the repetition-frequency-difference jitter and improvement in the measurement accuracy. Our work provides strong evidence and a promising way to trace the origin of dual-comb measurement errors in a single asynchronous soliton fiber laser.