High-Resolution Sensor System Using a Random Distributed Feedback Fiber Laser

In this paper, high-resolution measurements using random distributed feedback fiber lasers have been attained. A phase-shifted fiber Bragg grating is used to detect temperature shifts with a resolution under 0.01 °C. Due to the longitudinal-modeless behavior and the inherent frequency stability of random fiber lasers, the resolution limit of conventional fiber lasers has been overcome. The frequency shift of the grating is measured in the electrical domain by beating an external laser source with the laser line generated. A second setup that measures axial strain without the need of temperature compensation is also proposed and validated, reaching an axial strain resolution under 0.2 με.