High-speed narrow linewidth All-PM dispersive swept source for real-time FBG sensor interrogation

We present an environmentally stable, all-polarization-maintaining (PM) dispersion-based swept source system optimized for narrow linewidth and high-speed wavelength scanning, specifically tailored for fiber Bragg grating (FBG) sensor interrogation. The system integrates a chirped fiber Bragg grating (CFBG) as a highly dispersive element to balance scan speed and spectral resolution, enabling a compact cavity design and stable lasing. The laser achieves precise wavelength tuning over a 40 nm range in the telecom C-band, linewidth around 12 MHz, and an impressive scanning speed exceeding 3 MHz with stable output power of over 20 mW, outperforming mechanically tuned lasers. The all-PM design ensures robustness against environmental perturbations. We validate the performance through static and dynamic characterization, including linewidth narrowing via the spatial hole burning effect. Furthermore, we demonstrate its application in the interrogation of FBG sensor arrays in wavelength division multiplexing (WDM), time division multiplexing (TDM), and hybrid modes, as well as real-time dynamic strain sensing up to 1kHz. These results position the system as a scalable and robust solution for applications requiring rapid spectral acquisition and fine resolution, such as border security, biomedical imaging, and structural health monitoring.