Article

Extraordinary Optical Transmission Brightens Near-Field Fiber Probe

ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels (Barcelona), Spain.
Nano Letters (Impact Factor: 13.03). 02/2011; 11(2):355-60. DOI: 10.1021/nl102657m
Source: PubMed

ABSTRACT Near-field scanning optical microscopy (NSOM) offers high optical resolution beyond the diffraction limit for various applications in imaging, sensing, and lithography; however, for many applications the very low brightness of NSOM aperture probes is a major constraint. Here, we report a novel NSOM aperture probe that gives a 100× higher throughput and 40× increased damage threshold than conventional near-field aperture probes. These brighter probes facilitate near-field imaging of single molecules with apertures as small as 45 nm in diameter. We achieve this improvement by nanostructuring the probe and by employing a novel variant of extraordinary optical transmission, relying solely on a single aperture and a coupled waveguide. Comprehensive electromagnetic simulations show good agreement with the measured transmission spectra. Due to their significantly increased throughput and damage threshold, these resonant configuration probes provide an important step forward for near-field applications.

0 Bookmarks
 · 
342 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: This review focuses on the optical theory and applications of a single subwavelength aperture in a metal film. We begin with Bethe’s aperture theory for the optical transmission through a subwavelength aperture in a perfect electric conductor film and extend the discussion to apertures in real metals of finite thickness and to apertures with different shapes. Extraordinary optical transmission (EOT) is reviewed, particularly for an aperture in a transverse waveguide screen and for waveguide EOT with applications to aperture near-field probes. We overview applications of single subwavelength nanoapertures to refractive index sensing, single molecule fluorescence detection, Raman spectroscopy and optical trapping of dielectric nanoparticles, including biological matter. Finally, we discuss the potential of combining these many different capabilities to create greater functionality with a single aperture.
    08/2012; 1(4). DOI:10.1515/ntrev-2012-0028
  • [Show abstract] [Hide abstract]
    ABSTRACT: Near-field scanning optical microscopy (NSOM) is a powerful method for the optical imaging of surfaces with a resolution down to the nanometer scale. By focusing an external electromagnetic field to the subwavelength aperture or apex of a sharp tip, the diffraction limit is avoided and a near-field spot with a size on the order of the aperture or tip diameter can be created. This point light source is used for scanning a sample surface and recording the signal emitted from the small surface area that interacts with the near field of the probe. In tip-enhanced Raman spectroscopy, such a tip configuration can be used as well to record a full spectrum at each image point, from which chemically specific spectral images of the surface can be extracted. In either case, the contrast and resolution of the images depend critically on the properties of the NSOM probe used in the experiment. In this review, an overview of eligible tip properties and different approaches for tailoring specifically engineered NSOM probes is given from a fabrication point of view.
    08/2012; 1(4). DOI:10.1515/ntrev-2012-0027
  • [Show abstract] [Hide abstract]
    ABSTRACT: We propose to optically trap nanoparticles utilizing a single nanostructured glass-fiber tip. 3D translation of optically trapped nanoparticles - nano tweezers - presents vast application possibilities and has not yet been shown. The input end of the fibre probe is a standard fibre, providing easy coupling to a light source. The output end is tapered down and covered with gold, with a nanoaperture fabricated on the tip. The nanoaperture provides the strong field gradient necessary for trapping of nanoparticles. We discuss probe geometries supported by numerical simulations. The fabrication procedure for the fibre probe, using a focused ion beam, is described. A set-up for the experiments has been made and preliminary trapping results are presented.
    Conference on Complex Light and Optical Forces VIII; 02/2014

Full-text

Download
199 Downloads
Available from
May 16, 2014