title: Ultrathin high-index metasurfaces for shaping focused beams.
abstract: The volume size of a converging wave, which plays a relevant role in image resolution, is governed by the wavelength of the radiation and the numerical aperture (NA) of the wavefront. We designed an ultrathin (λ/8 width) curved metasurface that is able to transform a focused field into a high-NA optical architecture, thus boosting the transverse and (mainly) on-axis resolution. The elements of the metasurface are metal-insulator subwavelength gratings exhibiting extreme anisotropy with ultrahigh index of refraction for TM polarization. Our results can be applied to nanolithography and optical microscopy.
authors.forename: Mahin
authors.initials: M
authors.lastname: Naserpour
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Zapata-Rodríguez
authors.forename: Carlos
authors.initials: C
authors.lastname: Díaz-Aviñó
authors.forename: Mahdieh
authors.initials: M
authors.lastname: Hashemi
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Miret