摘要： Dual-comb spectroscopy (DCS) has experienced a remarkable growth propelled by recent advances in fiber and semiconductor technology. A key enabler for DCS is mutual stability between two repetition-rate-mismatched frequency combs, which conventionally relies on feedback loops employing additional optics and electronics to synchronize a pair of sources. This limitation can be overcome in several ways, of which one of the most promising is the generation of two frequency combs in a single free-running fiber laser cavity [1–3]. To date, however, the only configuration proven to be compatible with Doppler-limited spectroscopy was the dual-color laser presented in Ref. [2] requiring external spectral broadening, thus adding an extra layer of complexity. Here, we report on the realization of a drastically simplified all-fiber dual-comb laser (AFDCL) with an unprecedentedly low number of components and battery-operation-compatible electrical power consumption (0.35 W) with excellent suitability for spectroscopy of Doppler-limited transitions (Fig. 1). A key feature of our solution relying on polarization-multiplexing [3] is that the laser cavity has an easily adjustable repetition rate difference ranging from sub-kHz to dozens of kHz obtained by varying the intracavity polarization state using polarization controllers (PC) and/or the length of the polarization maintaining fiber in the cavity, which is not possible in the dual-color or bidirectional schemes. Furthermore, we achieve uninterrupted operation times of dozens of hours, and a record-high repetition rate for an AFDCL exceeding 140 MHz to maximize the optical power per comb tooth. High-resolution molecular dual-comb spectroscopy in free-running mode is made possible thanks to a novel real-time compatible phase correction algorithm that marks a radical departure from the cross-correlation or cross-ambiguity function paradigm, hence considerably lowering the complexity of such procedures. As a demonstration, we measure P18-P27 lines of the 2ν3 band of H13C14N at 10 Torr with FWHM Doppler line widths of ~450 MHz within 200 ms (Fig. 1b,c) with better than 1% of precision in a 1 THz bandwidth.