Nanofocusing of circularly polarized Bessel-type plasmon polaritons with hyperbolic metamaterials

miniature evanescent Bessel beam generator is realized by utilizing the combination of metasurfaces based on a concentric grating and hyperbolic metamaterials composed of alternate metal/dielectric multilayers. After introducing the plasmonic cavity lens, the feature size could be compressed to 62 nm (0.17k0) at the wavelength of 365 nm with a working distance as large as 100 nm. The theoretical models are verified by a set of experiments, providing a promising way to control light at the nanoscale.