Composite Structure Distributed Bragg Reflector Fiber Laser for Simultaneous Two-Parameter Sensing

We propose and demonstrate using a single composite structure distributed Bragg reflector fiber laser (DBR-FL) for simultaneous sensing of refractive index (RI) and temperature. The FL structure consists of a pair of uniform fiber Bragg gratings (FBGs) forming the laser cavity. A variable cavity attenuator made by a blazed FBG (BFBG) is written inside the cavity, which varies the optical loss upon changes in the surrounding RI. Simultaneous sensing is realized from the fact that the output power only varies with the surrounding RI, whereas the lasing wavelength with the temperature. The sensitivity of RI measurement of the proposed FL improved by several times in comparison with the passive BFBG sensor.