Extraordinary Optical Transmission Brightens Near-Field Fiber Probe

ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels (Barcelona), Spain.
Nano Letters (Impact Factor: 13.59). 02/2011; 11(2):355-60. DOI: 10.1021/nl102657m
Source: PubMed


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.

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Available from: Niek F Van Hulst, Oct 10, 2015
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    • "This generally limits the aperture diameter to around 50–100 nm, where the throughput efficiency is already as low as 10 −6 [21]. By altering the design of the nanoantenna at the aperture, nevertheless, it is possible to improve both spatial resolution and light throughput to ∼10 −3 [22], [23]. An alternative approach is to directly excite the antenna from the far-field without sending the light through the fiber as shown in Fig. 1(b). "
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    ABSTRACT: We present the use of fiber-based resonant dipole and nanogap optical nanoantennas for extreme resolution optical microscopy. A typical optical dipole antenna is only 100-nm long, as the wavelength of light is typically a million times smaller than for radio waves. We show how by focused-ion-beam milling of metal-coated tapered optical fibers we overcome the challenge of fabricating resonant antennas at such small-length scales, with an accuracy of 10 nm. The optical fiber provides an ideal interface between the macro- and nanoscales, allowing the manipulation of such a tiny nanoantenna with nanometer precision relative to a sample surface. Imaging single fluorescent molecules and nanobeads, we achieve an optical resolution down to 40 nm (FWHM), far below the Abbe diffraction limit. The strongly localized antenna field results in an enhancement of fluorescence up to 100 , while the vectorial nature of the local antenna field allows access to molecules of all orientations. Clearly, dedicated nanofabrication of fiber-based scanning optical antennas is a promising route to push the limits of optical nanoscopy.
    Journal of Lightwave Technology 06/2015; 33(12):2371-2377. DOI:10.1109/JLT.2014.2386132 · 2.97 Impact Factor
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    • "In practice, implementing SIBA trapping at the extremity of a tapered optical fiber first requires identifying a geometry of the SIBA trap enabling extended trapping times under low laser intensity, to prevent any photothermal damage at the fiber extremity. Typical damage threshold for such probes sits in the range of 10 10 W/m² concentrated at the tip apex [18]. In order to remain below this threshold, we focused our attention on the so-called BNA design [28] [29] [30]. "
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    ABSTRACT: Recent advances in nanotechnologies have prompted the need for tools to accurately and non-invasively manipulate individual nano-objects. Among the possible strategies, optical forces have been predicted to provide researchers with nano-optical tweezers capable of trapping a specimen and moving it in three dimensions. In practice, however, the combination of weak optical forces and photothermal issues has thus far prevented their experimental realization. Here, we demonstrate the first three-dimensional optical manipulation of single 50 nm dielectric objects with near-field nanotweezers. The nano-optical trap is built by engineering a bowtie plasmonic aperture at the extremity of a tapered metal-coated optical fibre. Both the trapping operation and monitoring are performed through the optical fibre, making these nanotweezers totally autonomous and free of bulky optical elements. The achieved trapping performances allow for the trapped specimen to be moved over tens of micrometres over a period of several minutes with very low in-trap intensities. This non-invasive approach is foreseen to open new horizons in nanosciences by offering an unprecedented level of control of nanosized objects, including heat-sensitive biospecimens.
    Nature Nanotechnology 03/2014; 9:295-299. DOI:10.1038/nnano.2014.24 · 34.05 Impact Factor
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    • "Unfortunately, small (<100 nm) apertures have limited optical throughput and the skin depth of real metals effectively increases the size of the aperture. While throughput can be increased by exploiting enhanced transmission effects35, the spatial resolution is still limited. To improve the spatial resolution while keeping the low-background noise, a tip-on-aperture design has been used whereby a small opening illuminates a protruding metallic tip36. "
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    ABSTRACT: We demonstrate the design, fabrication and characterization of a near-field plasmonic nanofocusing probe with a hybrid tip-plus-aperture design. By combining template stripping with focused ion beam lithography, a variety of aperture-based near-field probes can be fabricated with high optical performance. In particular, the combination of large transmission through a C-shaped aperture aligned to the sharp apex (<10 nm radius) of a template-stripped metallic pyramid allows the efficient delivery of light-via the C-shaped aperture-while providing a nanometric hotspot determined by the sharpness of the tip itself.
    Scientific Reports 05/2013; 3:1857. DOI:10.1038/srep01857 · 5.58 Impact Factor
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