对工作于1 064 nm波段的45°倾斜光纤光栅的偏振依赖损耗特性与工作机理进行了分析.利用紫外曝光法, 将周期为1 070 nm的常规相位模板旋转33°后, 在光敏光纤上写制了45°倾斜光纤光栅, 写制的光栅栅区长度为12 mm, 在1 040~1 085 nm范围内偏振依赖损耗值为7 dB左右.影响其偏振依赖损耗值的主要原因为相位模板的周期不是最佳值和栅区长度不够.利用写制的45°倾斜光纤光栅作为起偏器件, 实现了线偏振输出的掺镱光纤激光器, 其激光消光比高于30 dB, 输出波长为1 065.4 nm, 3 dB线宽为0.08 nm, 最高输出功率8.7 mW, 可长时间保持高偏振度稳定工作.

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.