All-Fiber Linear Polarized LP11 Mode Laser Based on Mode-Selective Polarization-Maintaining Fiber Bragg Gratings

We present a reliable and all-fiberized single-polarization, high-order mode fiber laser. The experimental setup employed polarization-maintaining ytterbium-doped fibers and a combination of different fiber Bragg gratings to achieve high mode purity and stable output. The system achieved a maximum output power of 3.8 W, a polarization extinction ratio (PER) of 96.7%, and a mode purity of 95.32% for the LP11 mode. Furthermore, the laser demonstrated notable stability; during a 120 min stability test, the standard deviation of the output power was measured at 0.15%, while the standard deviation of the polarization extinction ratio (PER) was 0.07%. This work offers a reliable solution for the generation of stable, high-purity LP11 mode lasers.