Dual-Comb Dynamic Interrogation of Fiber Bragg Grating with One Mode-Locked Fiber Laser

Dual-comb spectroscopy schemes have been demonstrated as an attractive solution for advanced optical spectroscopic analysis. The widely used fiber Bragg grating (FBG) sensing could benefit from the high spectral resolution and broad spectral coverage they could offer. However, the complexity, cost, and size of traditional dual-comb systems are prohibitively high for FBG applications. Dual-wavelength mode-locked fiber laser can generate two asynchronous ultrashort pulse trains and could enable the development of compact and low-complexity dual-comb application systems. In this paper, we propose and demonstrate a high-resolution, dynamic FBG interrogation scheme based on dual-comb spectroscopy with one free-running fiber laser. Accurate spectroscopic measurement of the FBG's reflective spectrum is realized with each acquired dual-comb interferogram without further averaging. In our experiments, the resolution of such single-shot FBG wavelength measurement results can reach 1.7 pm, while the spectral non-aliasing measurement range is over 10 nm. Enabled by this capability of making fast dual-comb spectroscopy measurement of the FBG sensor response, the sampling speed of the interrogation system can reach the repetition rate difference of the dual combs, e.g., 1 kHz in this demonstration. Dynamic measurements of FBG responses driven by frequency up to 400 Hz are experimentally demonstrated. Our results further illustrate the potential and advantages of such single-cavity dual-comb laser sources in realizing low-complexity dual-comb systems that could appeal to a wider variety of applications.