Abstract; Soliton frequency combs generated in microresonators offer powerful tools for optical metrology, due to its high time-frequency resolution. Here, via exciting the intracavity Brillouin laser in a high Q monolithic fiber resonator, we generate a pair of orthogonal Kerr soliton combs, which share the same repetition (≈ 1 GHz) but different central wavelengths (≈ 10 GHz). Difference of their carrier-envelope-offset frequencies (Δfceo) is determined by the Brillouin-resonance overlap spectrally. We find that beat notes of the Δfceo is mechanically sensitive to external force, demonstrating a high sensitivity 0.3 kHz/µN, with a linear measurement range up to 7.3 mN. Leveraging the noise-filtering and lock-in heterodyne measurement, we obtain a detect limit down to 520 pN. This work reveals a novel paradigm of dual-soliton microcomb multiplexing pumped by one single laser, and combines the ultrahigh resolution dual-comb strategy and fiber sensor technology. It may open a way towards the realization of versatile and powerful microcomb based sensors with simple structure, which could be widely attractive in precision measurements such as high precision gyroscope, mechanical tracing, and material science examination.
