Polarization ytterbium-doped fiber laser based on 45° tilted fiber grating

The working mechanism and Polarization Dependent Loss (PDL) characteristics of 45° tilted fiber gratings working at 1 064 nm band were researched theoretically and experimentally. The 45° tilted fiber grating was fabricated in photosensitive fiber by UV-inscription technique. A phase mask with a period of 1 070 nm was rotated 33° to the fiber axis to produce tilted fringes of 45° in the fiber core. The length of the 45° tilted fiber grating was about 12 mm. The PDL value was about 7 dB over 1 040 nm to 1 085 nm. According to theoretical analysis, the main causes of the low PDL value was due to the unsuitable pitch and insufficient length of the phase mask. Using the 45°tilted fiber grating as a polarization selective device, a polarized Yb-doped fiber laser was demonstrated. The polarization extinction ratio of the output laser was more than 30 dB. The maximum output power of the fiber laser was 8.7 mW and the center wavelength was 1 065.4 nm with 3 dB line width of 0.08 nm, which can be stable after a long time work.