Linearly-polarized operation of a Yb3+-doped double-clad fiber laser

In this work an all-fiber linearly-polarized Yb-doped double-clad fiber laser is proposed, in which the resonance cavity is composed of a pair of polarization maintaining fiber Bragg gratings (PM-FBGs). The polarization hole burning is enhanced by the selective polarization feedback by the PM-FBGs. A three-port polarization beam splitter with fiber pigtail was inserted into the laser cavity to select different polarization states. The laser features wavelength of 1069.72 nm and 1069.98 nm, output power of 125 mW, SNR of 45 dB, slope efficiency of 52%, as well as linewidth of 30.7 pm. The polarization characteristics of the laser are studied by measuring the laser power transmitted through a rotating Glan-Thomson polarizer. The degree of polarization of each lasing line is over 12 dB under different pump levels.