Subwavelength plasmonic lens patterned on a composite optical fiber facet for quasi-one-dimensional Bessel beam generation

We demonstrate a beam shaping method by engraving plasmonic lens consisted of subwavelength slit-metallic groove structure on the cleaved end facet of a composite optical fiber. The fiber consisted of a single mode optical fiber serially concatenated with a coreless silica fiber segment to expand the beam diameter. The subwavelength slit-groove structure on a gold film was fabri cated using focused ion beam milling process. Plasmonic interaction in the film generated a quasi-one-dimensional Bessel-like beam with a beam width of 0.8 μ m at the focal length of 2 μ m . Detailed two- and three-dimensional finite-difference time-domain analyses showed beam characteristics consistent with experimental observations.