title: Creation of a longitudinally polarized photonic nanojet via an engineered microsphere.
abstract: Dielectric microspheres exhibit the ability to focus an incident beam to a subwavelength spot with strong localized field intensity. In this Letter, a high beam quality of a longitudinally polarized electromagnetic component is created by decorating the surface of the microsphere with engineered structures. By changing the design of the engineered microspheres, the relative contribution of the longitudinal and radial components of a radially polarized incident beam to the photonic nanojet can be modified efficiently, leading to a sharp spot size which exceeds the optical diffraction limit. More importantly, a high conversion efficiency of 0.89 is achieved. At a wavelength of 633 nm, a focal spot of 266 nm (0.42λ) is achieved numerically by illuminating the engineered microsphere with a focusing beam at a numerical aperture of 0.7.
authors.forename: Mengxue
authors.initials: M
authors.lastname: Wu
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Ling
authors.forename: Zaichun
authors.initials: Z
authors.lastname: Chen
authors.forename: Xudong
authors.initials: X
authors.lastname: Chen
authors.forename: Rong
authors.initials: R
authors.lastname: Ji
authors.forename: Minghui
authors.initials: M
authors.lastname: Hong