Polarization-switched fiber optic ring laser for L-band multiwavelength remote sensing applications

This work presents the experimental demonstration of a three-channel remote sensor that operates in the L-band. It is based on a fiber ring laser cavity, formed by a semiconductor optical amplifier and three fiber Bragg gratings used both for the selection of the operating wavelengths and the sensing. A polarization-controller allows the activation of one, two or the three emission wavelengths simultaneously. The sensing elements can be situated in a remote localization, without compromising the temperature sensitivity of the experimental setup. To validate this functionality, a 25 km standard singlemode fiber optic reel is incorporated between the FBG-based sensors and the cavity, demonstrating the system's ability to perform long-range sensing while preserving signal integrity and operational reliability.