Generating cylindrical vector beams with subwavelength concentric metallic gratings fabricated on optical fibers

We report the generation of cylindrical vector beams using a concentric metallic grating fabricated on optical fibers with a period smaller than the wavelength of the incident light. Similar to the wiregrid linear polarizer, such a subwavelength metallic annular structure strongly reflects azimuthal polarization and allows radial polarization to transmit through. Due to the polarization selectivity of the concentric metallic grating, a cylindrical vector beam is obtained when a circularly polarized light is launched into the fiber. Such a device is suitable for the end mirror coupler in an all-fiber laser design to produce radially polarized modes.