Based on the few-mode fiber Bragg grating’s reflection characteristics, we propose and demonstrate a transverse modes switchable fiber laser fiber laser, fundamental mode and 1st higher order modes, and the states be switched by tuning the laser’s oscillating wavelength. The radial vector beam is also obtained by splitting the degenerated 1st higher order modes.
We present a numerical model for generating cylindrical vector beams (CVBs) through an ytterbium-doped few-mode
fiber laser. A practical numerical model based on propagation rate equations with consideration of propagating modes
competition between LP01 and LP11. To optimize the output power of LP11 while depress LP01, we analyze the
dependence of this competition on resonant wavelength, pump power, ytterbium doped fiber (YDF) length, doping
concentration and distribution. We also propose an effect method to completely depress the generation of LP01.