Preparation, package, and high-power fiber laser experiment of large mode-area fiber grating

The inscription method of FBGs on large-mode-area double-clad fibers (LMA-DCFs) with phase mask technique was described. A pair of LMA FBGs was prepared and the center wavelengths of them were both around 1076nm with 3 dB bandwidths of about 0.5nm. The reflectivities of them are 99% and 10% in the fundamental mode, respectively. In order to be protected and to withstand high-power laser, the FBGs were metally packaged, and then applied to an Yb 3+ -doped LMA-DCF laser as the laser cavity. An output power of 314 W centered at 1075.71 nm with a slope efficiency of 60% was achieved.