High‐Repetition‐Rate Single‐Cavity Dual‐Comb Fiber Laser With MHz Acquisition Speed

Dual‐comb technology has emerged as a powerful tool for high‐precision measurements, and single‐cavity dual‐comb (SC‐DC) stands out as a cost‐effective and readily available alternative owing to the elimination of complex systems. Yet, while acquisition rates exceeding MHz can enable more precise time‐variant analysis of transient events, achieving such high speeds in fiber SC‐DC systems has proven challenging. Cavity length management and device integration compound this approach, keeping demonstrated acquisition rates lingering at the kHz level for an extended period. Here, we demonstrate a compact, fiber‐based SC‐DC laser source with GHz‐level repetition rates and high repetition rate differences exceeding 1 MHz, which is over 2 orders of magnitude greater than conventional fiber SC‐DC sources. The system's capability is validated through ultrasonic vibration detection, successfully resolving transient mechanical motions above 110 kHz. This work provides a simplified, high‐performance dual‐comb solution that features speed and accessibility, opening avenues for field‐deployable high‐dynamic‐range sensing and spectroscopy.