39 research outputs found
A circular dielectric grating for vertical extraction of single quantum dot emission
We demonstrate a nanostructure composed of partially etched annular trenches
in a suspended GaAs membrane, designed for efficient and moderately broadband
(approx. 5 nm) emission extraction from single InAs quantum dots. Simulations
indicate that a dipole embedded in the nanostructure center radiates upwards
into free space with a nearly Gaussian far-field, allowing a collection
efficiency > 80 % with a high numerical aperture (NA=0.7) optic, and with 12X
Purcell radiative rate enhancement. Fabricated devices exhibit an approx. 10 %
photon collection efficiency with a NA=0.42 objective, a 20X improvement over
quantum dots in unpatterned GaAs. A fourfold exciton lifetime reduction
indicates moderate Purcell enhancement.Comment: (3 pages
Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler
We demonstrate a spectrally broadband and effcient technique for collecting
photoluminescence from a single InAs quantum dot directly into a standard
single mode optical fiber. In this approach, an optical fiber taper waveguide
is placed in contact with a suspended GaAs nanophotonic waveguide with embedded
quantum dots, forming an effcient and broadband directional coupler with
standard optical fiber input and output. Effcient photoluminescence collection
over a wavelength range of tens of nanometers is demonstrated, and a maximum
collection effciency of 6.05 % (corresponding single photon rate of 3.0 MHz)
into a single mode optical fiber was estimated for a single quantum dot
exciton
Moving boundary and photoelastic coupling in GaAs optomechanical resonators
Chip-based cavity optomechanical systems are being considered for
applications in sensing, metrology, and quantum information science. Critical
to their development is an understanding of how the optical and mechanical
modes interact, quantified by the coupling rate . Here, we develop GaAs
optomechanical resonators and investigate the moving dielectric boundary and
photoelastic contributions to . First, we consider coupling between the
fundamental radial breathing mechanical mode and a 1550 nm band optical
whispering gallery mode in microdisks. For decreasing disk radius from
m to m, simulations and measurements show that changes
from being dominated by the moving boundary contribution to having an equal
photoelastic contribution. Next, we design and demonstrate nanobeam
optomechanical crystals in which a GHz mechanical breathing mode couples
to a 1550 nm optical mode predominantly through the photoelastic effect. We
show a significant (30 ) dependence of on the device's in-plane
orientation, resulting from the difference in GaAs photoelastic coefficients
along different crystalline axes, with fabricated devices exhibiting
as high as 1.1 MHz for orientation along the [110] axis.
GaAs nanobeam optomechanical crystals are a promising system which can combine
the demonstrated large optomechanical coupling strength with additional
functionality, such as piezoelectric actuation and incorporation of optical
gain media
Nanoscale mapping and spectroscopy of non-radiative hyperbolic modes in hexagonal boron nitride nanostructures
The inherent crystal anisotropy of hexagonal boron nitride (hBN) sustains
naturally hyperbolic phonon polaritons, i.e. polaritons that can propagate with
very large wavevectors within the material volume, thereby enabling optical
confinement to exceedingly small dimensions. Indeed, previous research has
shown that nanometer-scale truncated nanocone hBN cavities, with deep
subwavelength dimensions, support three-dimensionally confined optical modes in
the mid-infrared. Due to optical selection rules, only a few of many such modes
predicted theoretically have been observed experimentally via far-field
reflection and scattering-type scanning near-field optical microscopy. The
Photothermal induced resonance (PTIR) technique probes optical and vibrational
resonances overcoming weak far-field emission by leveraging an atomic force
microscope (AFM) probe to transduce local sample expansion due to light
absorption. Here we show that PTIR enables the direct observation of previously
unobserved, dark hyperbolic modes of hBN nanostructures. Leveraging these
optical modes could yield a new degree of control over the electromagnetic
near-field concentration, polarization and angular momentum in nanophotonic
applications.Comment: 14 pages with references, 4 figure
Optical source of individual pairs of colour-conjugated photons
We theoretically demonstrate that Kerr nonlinearity in optical circuits can lead to both resonant four-wave mixing and photon blockade, which can be used for high-yield generation of high-fidelity individual photon pairs with conjugated frequencies. We propose an optical circuit, which, in the optimal pulsed-drive regime, would produce photon pairs at the rate up to 5âĂâ105â sâ1 (0.5 pairs per pulse) with g(2)(0)<10â2g(2)(0)<10â2 for one of the conjugated frequencies. We show that such a scheme can be utilised to generate colour-entangled photons
Waveguide Coupled Resonance Fluorescence from On-Chip Quantum Emitter
Resonantly driven quantum emitters offer a very promising route to obtain highly coherent sources of single photons required for applications in quantum information processing (QIP). Realizing this for on-chip scalable devices would be important for scientific advances and practical applications in the field of integrated quantum optics. Here we report on-chip quantum dot (QD) resonance fluorescence (RF) efficiently coupled into a single-mode waveguide, a key component of a photonic integrated circuit, with a negligible resonant laser background and show that the QD coherence is enhanced by more than a factor of 4 compared to off-resonant excitation. Single-photon behavior is confirmed under resonant excitation, and fast fluctuating charge dynamics are revealed in autocorrelation g(2) measurements. The potential for triggered operation is verified in pulsed RF. These results pave the way to a novel class of integrated quantum-optical devices for on-chip quantum information processing with embedded resonantly driven quantum emitters
Micro-combs: a novel generation of optical sources
The quest towards the integration of ultra-fast, high-precision optical clocks is reflected in the large number of high-impact papers on the topic published in the last few years. This interest has been catalysed by the impact that high-precision optical frequency combs (OFCs) have had on metrology and spectroscopy in the last decade [1â5]. OFCs are often referred to as optical rulers: their spectra consist of a precise sequence of discrete and equally-spaced spectral lines that represent precise marks in frequency. Their importance was recognised worldwide with the 2005 Nobel Prize being awarded to T.W. HĂ€nsch and J. Hall for their breakthrough in OFC science [5]. They demonstrated that a coherent OFC source with a large spectrum â covering at least one octave â can be stabilised with a self-referenced approach, where the frequency and the phase do not vary and are completely determined by the source physical parameters. These fully stabilised OFCs solved the challenge of directly measuring optical frequencies and are now exploited as the most accurate time references available, ready to replace the current standard for time. Very recent advancements in the fabrication technology of optical micro-cavities [6] are contributing to the development of OFC sources. These efforts may open up the way to realise ultra-fast and stable optical clocks and pulsed sources with extremely high repetition-rates, in the form of compact and integrated devices. Indeed, the fabrication of high-quality factor (high-Q) micro-resonators, capable of dramatically amplifying the optical field, can be considered a photonics breakthrough that has boosted not only the scientific investigation of OFC sources [7â13] but also of optical sensors and compact light modulators [6,14]
2022 Roadmap on integrated quantum photonics
AbstractIntegrated photonics will play a key role in quantum systems as they grow from few-qubit prototypes to tens of thousands of qubits. The underlying optical quantum technologies can only be realized through the integration of these components onto quantum photonic integrated circuits (QPICs) with accompanying electronics. In the last decade, remarkable advances in quantum photonic integration have enabled table-top experiments to be scaled down to prototype chips with improvements in efficiency, robustness, and key performance metrics. These advances have enabled integrated quantum photonic technologies combining up to 650 optical and electrical components onto a single chip that are capable of programmable quantum information processing, chip-to-chip networking, hybrid quantum system integration, and high-speed communications. In this roadmap article, we highlight the status, current and future challenges, and emerging technologies in several key research areas in integrated quantum photonics, including photonic platforms, quantum and classical light sources, quantum frequency conversion, integrated detectors, and applications in computing, communications, and sensing. With advances in materials, photonic design architectures, fabrication and integration processes, packaging, and testing and benchmarking, in the next decade we can expect a transition from single- and few-function prototypes to large-scale integration of multi-functional and reconfigurable devices that will have a transformative impact on quantum information science and engineering
Pseudocyst formation after abdominal liposuction-extravasations of Morel-Lavallee on MR images
A swelling of the abdominal watt in a 27-year-old woman after undergoing liposuction is described. Pseudocyst of Morel-Lavallee was located within the abdominal fascia and removed by surgery. MRI showed a non-homogenous mass with hyper intense fluid level and septations in T2-weighted images. We speculated that MRI can be used to guide the treatment (conservative or surgical). the literature concerning liposuction is reviewed. (c) 2005 the British Association of Plastic Surgeons. Published by Elsevier B.V. All rights reserved.Universidade Federal de SĂŁo Paulo, Dept Diagnost Imaging, SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Dept Plast Surg, SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Dept Diagnost Imaging, SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Dept Plast Surg, SĂŁo Paulo, BrazilWeb of Scienc