282 research outputs found
Spatio-temporal second-order quantum correlations of surface plasmon polaritons
We present an experimental methodology to observe spatio-temporal
second-order quantum coherence of surface plasmon polaritons which are emitted
by nitrogen vacancy color centers attached at the apex of an optical tip. The
approach relies on leakage radiation microscopy in the Fourier space and we use
this approach to test wave-particle duality for surface plasmon polaritons
Single and dual fiber nano-tip optical tweezers: trapping and analysis
An original optical tweezers using one or two chemically etched fiber
nano-tips is developed. We demonstrate optical trapping of 1 micrometer
polystyrene spheres at optical powers down to 2 mW. Harmonic trap potentials
were found in the case of dual fiber tweezers by analyzing the trapped particle
position fluctuations. The trap stiffness was deduced using three different
models. Consistent values of up to 1 fN/nm were found. The stiffness linearly
decreases with decreasing light intensity and increasing fiber tip-to-tip
distance
Large variation in the boundary-condition slippage for a rarefied gas flowing between two surfaces
We study the slippage of a gas along mobile rigid walls in the sphere-plane
confined geometry and find that it varies considerably with pressure. The
classical no-slip boundary condition valid at ambient pressure changes
continuously to an almost perfect slip condition in a primary vacuum. Our study
emphasizes the key role played by the mean free-path of the gas molecules on
the interaction between a confined fluid and solid surfaces and further
demonstrates that the macroscopic hydrodynamics approach can be used with
confidence even in a primary vacuum environment where it is intuitively
expected to fail
Casimir force measurements in Au-Au and Au-Si cavities at low temperature
We report on measurements of the Casimir force in a sphere-plane geometry
using a cryogenic force microscope to move the force probe in situ over
different materials. We show how the electrostatic environment of the
interacting surfaces plays an important role in weak force measurements and can
overcome the Casimir force at large distance. After minimizing these parasitic
forces, we measure the Casimir force between a gold-coated sphere and either a
gold-coated or a heavily doped silicon surface in the 100-400 nm distance
range. We compare the experimental data with theoretical predictions and
discuss the consequence of a systematic error in the scanner calibration on the
agreement between experiment and theory. The relative force over the two
surfaces compares favorably with theory at short distance, showing that this
Casimir force experiment is sensitive to the dielectric properties of the
interacting surfaces.Comment: accepted for publication in Physical Review
Near-field microscopy with a scanning nitrogen-vacancy color center in a diamond nanocrystal: A brief review
We review our recent developments of near-field scanning optical microscopy
(NSOM) that uses an active tip made of a single fluorescent nanodiamond (ND)
grafted onto the apex of a substrate fiber tip. The ND hosting a limited number
of nitrogen-vacancy (NV) color centers, such a tip is a scanning quantum source
of light. The method for preparing the ND-based tips and their basic properties
are summarized. Then we discuss theoretically the concept of spatial resolution
that is achievable in this special NSOM configuration and find it to be only
limited by the scan height over the imaged system, in contrast with the
standard aperture-tip NSOM whose resolution depends critically on both the scan
height and aperture diameter. Finally, we describe a scheme we have introduced
recently for high-resolution imaging of nanoplasmonic structures with ND-based
tips that is capable of approaching the ultimate resolution anticipated by
theory.Comment: AD, AC, OM, MB and SH wish to dedicate this brief review article to
their co-author and colleague Yannick Sonnefraud who passed away in September
2014. Yannick initiated this research in 200
Plasmonic interferometry: probing launching dipoles in scanning-probe plasmonics
We develop a semi-analytical method for analyzing surface plasmon
interferometry using near-field scanning optical sources. We compare our
approach to Young double hole interferometry experiments using scanning
tunneling microscope (STM) discussed in the literature and realize experiments
with an aperture near-field scanning optical microscope (NSOM) source
positioned near a ring like aperture slit milled in a thick gold film. In both
cases the agreement between experiments and model is very good. We emphasize
the role of dipole orientations and discuss the role of magnetic versus
electric dipole contributions to the imaging process as well as the
directionality of the effective dipoles associated with the various optical and
plasmonic sources.Comment: To appear in Journal of Applied Physics (2014
Highly efficient singular surface plasmon generation by achiral apertures
We report a highly efficient generation of singular surface plasmon (SP)
field by an achiral plasmonic structure consisting of -shaped
apertures. Our quantitative analysis based on leakage radiation microscopy
(LRM) demonstrates that the induced spin-orbit coupling can be tuned by
adjusting the apex angle of the -shaped aperture. Specifically, the
array of -shaped apertures with the apex angle is shown to
give rise to the directional coupling efficiency. The ring of -shaped
apertures with the apex angle realized to generate the maximum
extinction ratio (ER=11) for the SP singularities between two different
polarization states. This result provides a more efficient way for developing
SP focusing and SP vortex in the field of nanophotonics such as optical
tweezers
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