Nanofocusing in laterally tapered plasmonic waveguides.

Center for Nanophotonics, FOM-Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
Optics Express (Impact Factor: 3.53). 01/2008; 16(1):45-57. DOI: 10.1364/OE.16.000045
Source: PubMed

ABSTRACT We investigate the focusing of surface plasmon polaritons (SPPs) excited with 1.5 microm light in a tapered Au waveguide on a planar dielectric substrate by experiments and simulations. We find that nanofocusing can be obtained when the asymmetric bound mode at the substrate side of the metal film is excited. The propagation and concentration of this mode to the tip is demonstrated. No sign of a cutoff waveguide width is observed as the SPPs propagate along the tapered waveguide. Simulations show that such concentrating behavior is not possible for excitation of the mode at the low-index side of the film. The mode that enables the focusing exhibits a strong resemblance to the asymmetric mode responsible for focusing in conical waveguides. This work demonstrates a practical implementation of plasmonic nanofocusing on a planar substrate.

Download full-text


Available from: Laurens Kuipers, Jan 28, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Surface plasmons polaritons (SPPs) at metal/dielectric interfaces have raised lots of expectations in the on-going quest towards scaling down optical devices. SPP optics offers a powerful and flexible platform for real two-dimensional integrated optics, capable of supporting both light and electrons. Yet, a full exploitation of the features of SPPs is conditioned by an accurate control of their flow. Most efforts have so far focused on the extrapolation of concepts borrowed from guided optics. This strategy has already led to many important breakthroughs but a fully deterministic control of SPP modes remains a challenge. Recently, the field of optics was stimulated by a novel paradigm, transformation optics, which offers the capability to control light flow in any desired fashion. While it has already significantly contributed to the design of metamaterials with unprecedented optical properties, its versatility offers new opportunities towards a fully deterministic control of SPPs and the design of a new class of plasmonic functionalities. Here, we review recent progress in the application of transformation optics to SPPs. We first briefly describe the theoretical formalism of transformation plasmonics, focusing on its specificities over its three-dimensional optical counterpart. Numerical simulations are then used to illustrate its capability to tame SPP flows at a metal interface patterned with a dielectric load. Finally, we review recent experimental implementations leading to unique SPP functionalities at optical frequencies.
    07/2012; 1(1-1):51-64. DOI:10.1515/nanoph-2012-0011
  • [Show abstract] [Hide abstract]
    ABSTRACT: Micro/nanostructure photonic devices offer a variety of enabling properties, including low power-consumption, cost-efficient, compact size, and reliability. These distinctive features have been exploited in a wealth of applications ranging from telecommunication and optical interconnect to photonic network on chip. In this paper, we review two main classes of micro/nanostructure photonic devices, to provide the kinds of functions for optical signal processing. Keywordsphotonic nano-device–optical signal processing–micro/nano optical fiber–silicon plasmonic waveguide
    Frontiers of Optoelectronics in China 09/2011; 4(3):254-263. DOI:10.1007/s12200-011-0136-y
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three types of indirect phase tuning-based plasmonic structures with subwavelength circular grooves/slits and/or central apertures corrugated on Au film supported by glass substrate: depth modulation, width modulation, and hybrid depth-width modulation, were put forth in this paper. They were investigated experimentally by means of nanofabrication and near-filed scanning optical microscope characterization. The plasmonic structures were fabricated using the technique of focused ion beam direct milling. Our experimental results demonstrated that all of the phase tuning-based structures have focusing functions. Both the width and depth modulation-based structures can realize beam focusing and produce an elongated depth of focus. Moreover, after comparison among these three structures, we found that the width modulation-based structure has the best focusing performance. KeywordsPlasmonic structures–NSOM–FIB–Indirect phase modulation
    Plasmonics 06/2011; 6(2):227-233. DOI:10.1007/s11468-010-9192-1 · 2.74 Impact Factor