106 research outputs found
Molecules as Sources for Indistinguishable Single Photons
We report on the triggered generation of indistinguishable photons by
solid-state single-photon sources in two separate cryogenic laser scanning
microscopes. Organic fluorescent molecules were used as emitters and
investigated by means of high resolution laser spectroscopy. Continuous-wave
photon correlation measurements on individual molecules proved the isolation of
single quantum systems. By using frequency selective pulsed excitation of the
molecule and efficient spectral filtering of its emission, we produced
triggered Fourier-limited single photons. In a further step, local electric
fields were applied to match the emission wavelengths of two different
molecules via Stark effect. Identical single photons are indispensible for the
realization of various quantum information processing schemes proposed. The
solid-state approach presented here prepares the way towards the integration of
multiple bright sources of single photons on a single chip.Comment: Accepted for publication in J. Mod. Opt. This is the original
submitted versio
A scanning microcavity for in-situ control of single-molecule emission
We report on the fabrication and characterization of a scannable Fabry-Perot
microcavity, consisting of a curved micromirror at the end of an optical fiber
and a planar distributed Bragg reflector. Furthermore, we demonstrate the
coupling of single organic molecules embedded in a thin film to well-defined
resonator modes. We discuss the choice of cavity parameters that will allow
sufficiently high Purcell factors for enhancing the zero-phonon transition
between the vibrational ground levels of the electronic excited and ground
states.Comment: 8 page
A planar dielectric antenna for directional single-photon emission and near-unity collection efficiency
Single emitters have been considered as sources of single photons in various
contexts such as cryptography, quantum computation, spectroscopy, and
metrology. The success of these applications will crucially rely on the
efficient directional emission of photons into well-defined modes. To
accomplish a high efficiency, researchers have investigated microcavities at
cryogenic temperatures, photonic nanowires, and near-field coupling to metallic
nano-antennas. However, despite an impressive progress, the existing
realizations substantially fall short of unity collection efficiency. Here we
report on a theoretical and experimental study of a dielectric planar antenna,
which uses a layered structure for tailoring the angular emission of a single
oriented molecule. We demonstrate a collection efficiency of 96% using a
microscope objective at room temperature and obtain record detection rates of
about 50 MHz. Our scheme is wavelength-insensitive and can be readily extended
to other solid-state emitters such as color centers and semiconductor quantum
dots
Quantum Interference of Tunably Indistinguishable Photons from Remote Organic Molecules
We demonstrate two-photon interference using two remote single molecules as
bright solid-state sources of indistinguishable photons. By varying the
transition frequency and spectral width of one molecule, we tune and explore
the effect of photon distinguishability. We discuss future improvements on the
brightness of single-photon beams, their integration by large numbers on chips,
and the extension of our experimental scheme to coupling and entanglement of
distant molecules
Quantum Degenerate Exciton-Polaritons in Thermal Equilibrium
We study the momentum distribution and relaxation dynamics of semiconductor
microcavity polaritons by angle-resolved and time-resolved spectroscopy. Above
a critical pump level, the thermalization time of polaritons at positive
detunings becomes shorter than their lifetime, and the polaritons form a
quantum degenerate Bose-Einstein distribution in thermal equilibrium with the
lattice.Comment: Updated with the published versio
Controlled coupling of counterpropagating whispering-gallery modes by a single Rayleigh scatterer: a classical problem in a quantum optical light
We present experiments where a single subwavelength scatterer is used to
examine and control the back-scattering 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.Comment: accepted for publication in Pysical Review Letter
Swept source / Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit
Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050nm at 100kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not require active polarization modulating devices. This advance decreases system cost and avoids complex synchronization requirements. The polarization delay unit was implemented in the sample beam path in order to simultaneously illuminate the sample with two different polarization states. The orthogonal polarization components for the depth-multiplexed signals from the two input states were detected using dual balanced detection. PS-OCT images were computed using Jones calculus. 3D PS-OCT imaging was performed in the human and rat retina. In addition to standard OCT images, PS-OCT images were generated using contrast form birefringence and depolarization. Enhanced tissue discrimination as well as quantitative measurements of sample properties was demonstrated using the additional contrast and information contained in the PS-OCT images.National Institutes of Health (U.S.) (NIH R01-EY011289-25)National Institutes of Health (U.S.) (R01-EY013178-12)National Institutes of Health (U.S.) (R01-EY013516-09)National Institutes of Health (U.S.) (R01-EY019029-04)National Institutes of Health (U.S.) (R01-EY018184-05)National Institutes of Health (U.S.) (R01-CA075289-14)National Institutes of Health (U.S.) (R01-HL095717-03)National Institutes of Health (U.S.) (R01-NS057476-05)United States. Air Force Office of Scientific Research (AFOSR FA9550-10-1-0063)United States. Dept. of Defense. Medical Free Electron Laser Program (FA9550-07-1-0101
Spontaneous emission enhancement of a single molecule by a double-sphere nanoantenna across an interface
We report on two orders of magnitude reduction in the fluorescence lifetime
when a single molecule placed in a thin film is surrounded by two gold
nanospheres across the film interface. By attaching one of the gold particles
to the end of a glass fiber tip, we could control the modification of the
molecular fluorescence at will. We find a good agreement between our
experimental data and the outcome of numerical calculations
Исследование датчиков рН и удельной электрической проводимости фирмы WTW в системе автоматизированного контроля качества очистки сточных вод
We demonstrate the suitability of microcavities based on circular grating resonators (CGRs) as fast switches. This type of optical resonator is characterized by a high quality factor and very small mode volume. The waveguide-coupled CGRs are fabricated with silicon-on-insulator technology compatible with standard complementary metal-oxide semiconductor (CMOS) processing. The linear optical properties of the CGRs are investigated by transmission spectroscopy. From 3D finite-difference time-domain simulations of isolated CGRs, we identify the measured resonances. We probe the spatial distribution and the parasitic losses of a resonant optical mode with scanning near-field optical microscopy. We observe fast all-optical switching within a few picoseconds by optically generating free charge carriers within the cavity. (C) 2009 Optical Society of Americ
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