Analysis of Generating Cylindrical Vector Beams Using a Few-Mode Fiber Bragg Grating

An efficient numerical model is proposed to generate cylindrical vector (CV) beams by use of a few-mode fiber Bragg grating (FM-FBG) written directly in an ytterbium-doped fiber (YDF). Based on multilayer method, we analysis the transverse modes competition between LP ₀₁ and LP ₁₁ modes under various conditions. We propose that a pure CV beam can be generated by completely depressing LP ₀₁ mode through a doughnut doping few-mode fiber or using a wavelength filter.