In this work we present results on the use of optical nanofibers of subwavelength diameter as interfaces for probing and manipulating laser-cooled rubidium atoms. In particular, we concentrate on photon counts emitted through the nanofiber.
Tapered optical fiber with subwavelength diameter waist, an optical nanofiber, provides a unique and versatile platform for manipulating atoms and photons. In the guided modes of the nanofibers, the optical field can be tightly confined in the transverse direction while enabling strong interaction with the surrounding medium in the evanescent region. Combining laser-cooled atoms with nanofibers has enabled surprising quantum optics experiments, e.g. the efficient channeling of emission from single atoms into the fiber-guided modes, spectroscopy of near-surface atoms, high optical depth with an array of atoms optically trapped around the nanofiber, atomic memories and Bragg reflectors for fiber-guided photons, chiral light-matter interaction etc. In addition, using moderate longitudinal confinement in nanofiber cavities has enabled strong coupling between a single atom and fiber-guided photons. In this article, I review some of the key experimental demonstrations on the “atom+nanofiber” platform.
We discuss how subwavelength-diameter silica-fibers, "optical nanofibers", can open new perspectives for manipulating atoms and photons. We explore atom/photon interaction around a nanofiber using laser-cooled Cs-atoms. We show that single atoms on a nanofiber can work as an optically dense medium which may give a novel work medium for slow light through an optical fiber. Basic characteristics for single atoms on a nanofiber; spontaneous emission, single-atom trapping, photoabsorption, and quantum interference, are discussed.
We demonstrate how optical nanofibers can be used to manipulate and probe single-atom fluorescence. We show that fluorescence photons from a very small number of atoms, average atom number of less than 0.1, around the nanofiber can readily be observed through single-mode optical fiber under resonant laser irradiation. We show also that optical nanofibers enable us to probe the van der Waals interaction between atoms and surface with high precision by observing the fluorescence excitation spectrum.