Dual Micro-comb Generation in Fiber Laser Driven by Single Ultra-High-Q Microfiber Resonator

Dual-comb technology opens the route to a broad range of applications in science and engineering in past decades, and the progress in microresonator-generated optical frequency combs (micro-combs) has promoted the dual-comb system to a new level of integration and high speed. However, the problem of self-starting has yet been fully addressed for conventional external pumps, along with the high tape-out cost and low fiber-system-compatibility for the core on-chip resonators. Here a low-cost all-fiber dual-comb source is demonstrated without an external pump by nesting one single microfiber resonator into a fiber laser cavity. The key resonator device features a record-high Q-factor of 10⁷ in the microfiber scheme and an inherent structural birefringence, enabling a polarization-multiplexed parametric process for dual-comb generation. For the first time, the micro-comb gets boosted in a microfiber resonator, and the typical super mode instability in the laser cavity comb is successfully suppressed. Our work highlights the ultra-high-Q microfiber resonator for a practicable and simply equipped alternative to generate micro-combs for potential applications.