We apply two- and three-dimensional numerical calculations to study optical nanoantennae made of two coupled gold nanostructures, enclosing a single emitter in their gap. We show that, using structures manufacturable with today's nanotechnology, it is possible to increase the radiative decay rate by three orders of magnitude while keeping a quantum efficiency larger than 80% in the near-infrared regime. We examine the competition between the radiative and nonradiative processes in the presence of the antennae as a function of wavelength and antenna geometry. Our results hold great promise for improving the quantum efficiency of poor emitters such as silicon nanocrystals or carbon nanotubes. (c) 2007 Optical Society of America.
Scanning near-field optical coherent spectroscopy of single molecules at 1.4 K
Ilja Gerhardt,
Gert Wrigge,
Mario Agio,
Pavel Bushev,
Gert Zumofen,
Vahid Sandoghdar
We present scanning near-field extinction spectra of single molecules embedded in a solid matrix. By varying the tip-molecule separation, we modify the line shape of the spectra, demonstrating the coherent nature of the interaction between the incident laser light and the excited state of the molecule. We compare the measured data with the outcome of numerical calculations and find a very good agreement. (c) 2007 Optical Society of America.
Near-field imaging and frequency tuning of a high-Q photonic crystal membrane microcavity
S. Mujumdar,
A. F. Koenderink,
T. Suenner,
B. C. Buchler,
M. Kamp,
A. Forchel,
Vahid Sandoghdar
We discuss experimental studies of the interaction between a nanoscopic object and a photonic crystal membrane resonator of quality factor Q=55000. By controlled actuation of a glass fiber tip in the near field of the photonic crystal, we constructed a complete spatio-spectral map of the resonator mode and its coupling with the fiber tip. On the one hand, our findings demonstrate that scanning probes can profoundly influence the optical characteristics and the near-field images of photonic devices. On the other hand, we show that the introduction of a nanoscopic object provides a low loss method for on-command tuning of a photonic crystal resonator frequency. Our results are in a very good agreement with the predictions of a combined numerical/analytical theory. (C) 2007 Optical Society of America.
Nanoparticle-induced fluorescence lifetime modification as nanoscopic ruler: Demonstration at the single molecule level
J. Seelig,
K. Leslie,
A. Renn,
S. Kuhn,
V. Jacobsen,
M. van de Corput,
C. Wyman,
Vahid Sandoghdar
We combine interferometric detection of single gold nanoparticles, single molecule microscopy, and fluorescence lifetime measurement to study the modification of the fluorescence decay rate of an emitter close to a nanoparticle. In our experiment, gold particles with a diameter of 15 nm were attached to single dye molecules via double-stranded DNA of different lengths. Nanoparticle-induced lifetime modification (NPILM) has promise in serving as a nanoscopic ruler for the distance range well beyond 10 nm, which is the upper limit of fluorescence resonant energy transfer (FRET). Furthermore, the simultaneous detection of single nanoparticles and fluorescent molecules presented in this work provides new opportunities for single molecule biophysical studies.
Strong extinction of a laser beam by a single molecule
I. Gerhardt,
G. Wrigge,
P. Bushev,
G. Zumofen,
M. Agio,
R. Pfab,
Vahid Sandoghdar
We present an experiment where a single molecule strongly affects the amplitude and phase of a laser field emerging from a subwavelength aperture. We achieve a visibility of -6% in direct and +10% in cross-polarized detection schemes. Our analysis shows that a close to full extinction should be possible using near-field excitation.
Label-free optical detection and tracking of single virions bound to their receptors in supported membrane bilayers
Helge Ewers,
Volker Jacobsen,
Enrico Klotzsch,
Alicia E. Smith,
Ari Helenius,
Vahid Sandoghdar
We apply an interferometric optical detection scheme to image and track unlabeled single virions. Individual simian virus 40 virions and uninfectious virus-like particles were imaged on a glass substrate and on a supported membrane bilayer. Moreover, single unlabeled virions were tracked when bound to supported membrane bilayers via the viral receptor, the glycolipid GM1. The technology presented here promises to be generally applicable to studying the motion of unlabeled macromolecules on membranes.
Nano-optomechanical characterization and manipulation of photonic crystals
Sushil Mujumdar,
A. Femius Koenderink,
Robert Wuest,
Vahid Sandoghdar
IEEE Journal of Selected Topics in Quantum Electronics
13
253-261
(2007)
| Journal
We describe the application of scanning near-field optical microscopy (SNOM) for the high-resolution visualization of light propagation in photonic crystal structures. We also demonstrate that nanoscopic elements such as sharp tips could be used for the mechanical manipulation of the optical properties of photonic crystals. In particular, our theoretical and experimental results show that narrow resonances of a photonic crystal cavity can be tuned without a substantial influence on its quality factor. Furthermore, we discuss the modification of the fluorescence of a nanoscopic emitter as a function of its location close to a photonic crystal.
Linear and non-linear optical experiments based on macroporous silicon photonic crystals
Ralf B. Wehrspohn,
Stefan L. Schweizer,
Vahid Sandoghdar
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
204
(11)
3708-3726
(2007)
| Journal
Macroporous silicon is a model system for 2D silicon photonic crystals. In this review, we describe our recent theoretical and experimental advances in the macroporous silicon technology as well as in novel near-field optical experiments concerning modified light emission from photonic crystal cavities and waveguides. We also review our recent work on tuning silicon photonic crystals by free-carriers or nonlinear effects and compare the two tuning mechanisms. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Realization of two Fourier-limited solid-state single-photon sources
R. Lettow,
V. Ahtee,
R. Pfab,
A. Renn,
E. Ikonen,
Stephan Götzinger,
Vahid Sandoghdar
We demonstrate two solid-state sources of indistinguishable single photons. High resolution laser spectroscopy and optical microscopy were combined at T = 1.4 K to identify individual molecules in two independent microscopes. The Stark effect was exploited to shift the transition frequency of a given molecule and thus obtain single photon sources with perfect spectral overlap. Our experimental arrangement sets the ground for the realization of various quantum interference and information processing experiments. (c) 2007 Optical Society of America.
Controlled coupling of counterpropagating whispering-gallery modes by a single Rayleigh scatterer: A classical problem in a quantum optical light
A. Mazzei,
Stephan Götzinger,
L. de S. Menezes,
G. Zumofen,
O. Benson,
Vahid Sandoghdar
We present experiments where a single subwavelength scatterer is used to examine and control the backscattering induced coupling between counterpropagating high-Q modes of a microsphere resonator. Our measurements reveal the standing wave character of the resulting symmetric and antisymmetric eigenmodes, their unbalanced intensity distributions, and the coherent nature of their coupling. We discuss our findings and the underlying classical physics in the framework common to quantum optics and provide a particularly intuitive explanation of the central processes.
Finite-difference time-domain modeling of decay rates in the near field of metal nanostructures
F. Kaminski,
Vahid Sandoghdar,
M. Agio
Journal of Computational and Theoretical Nanoscience
4
635-643
(2007)
| Journal
We test the three-dimensional finite-difference time-domain method for the calculation of decay rates of an emitter placed in close vicinity to metal nanostructures. By choosing analytical solvable systems we asses its accuracy and indicate the issues deriving from near-field coupling, Ohmic losses and staircasing. The latter is found to be the most problematic one, because it gives rise to spurious peaks that survive even for very fine discretizations.
Contact
Nano-Optics Division Prof. Vahid Sandoghdar
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
