On-line temperature measurement of fiber Bragg gratings inside a fiber laser

We propose an on-line measurement approach for the temperature of fiber Bragg gratings (FBGs) inside a fiber laser. To demonstrate this method, a narrow linewidth fiber ring laser is set up employing a π-phase shift FBG and a highly reflective FBG, and then the core-temperature is obtained by detecting the operating wavelength of the laser due to the temperature characteristics of the FBGs. This paper provides a real-time, rapid method to detect the core-temperature of FBGs in fiber lasers, which can be used in study of high power fiber lasers.