28 research outputs found
Small Satellites Constellations & Network: Architectures and Technologies
Based on two constellation missions cases ( data collect and disaster monitoring by SAR radar ), the study derives architectural and related technologies required in the field of future commercial « small » onstellations. Global management from centralized control station is chosen here, with intermitent inter-plan visibility for 1SL, as imposed by the low altitude and moderatly populated parameters
Properties of a single photon generated by a solid-state emitter: effects of pure dephasing
We investigate the properties of a single photon generated by a solid-state
emitter subject to strong pure dephasing. We employ a model in which all the
elements of the system, including the propagating fields, are treated quantum
mechanically. We analytically derive the density matrix of the emitted photon,
which contains full information about the photon, such as its pulse profile,
power spectrum, and purity. We visualize these analytical results using
realistic parameters and reveal the conditions for maximizing the purity of
generated photons.Comment: 25pages(one column), 10 figure
Non-resonant dot-cavity coupling and its applications in resonant quantum dot spectroscopy
We present experimental investigations on the non-resonant dot-cavity
coupling of a single quantum dot inside a micro-pillar where the dot has been
resonantly excited in the s-shell, thereby avoiding the generation of
additional charges in the QD and its surrounding. As a direct proof of the pure
single dot-cavity system, strong photon anti-bunching is consistently observed
in the autocorrelation functions of the QD and the mode emission, as well as in
the cross-correlation function between the dot and mode signals. Strong Stokes
and anti-Stokes-like emission is observed for energetic QD-mode detunings of up
to ~100 times the QD linewidth. Furthermore, we demonstrate that non-resonant
dot-cavity coupling can be utilized to directly monitor and study relevant QD
s-shell properties like fine-structure splittings, emission saturation and
power broadening, as well as photon statistics with negligible background
contributions. Our results open a new perspective on the understanding and
implementation of dot-cavity systems for single-photon sources, single and
multiple quantum dot lasers, semiconductor cavity quantum electrodynamics, and
their implementation, e.g. in quantum information technology.Comment: 17 pages, 4 figure
I-HAZE: a dehazing benchmark with real hazy and haze-free indoor images
Image dehazing has become an important computational imaging topic in the
recent years. However, due to the lack of ground truth images, the comparison
of dehazing methods is not straightforward, nor objective. To overcome this
issue we introduce a new dataset -named I-HAZE- that contains 35 image pairs of
hazy and corresponding haze-free (ground-truth) indoor images. Different from
most of the existing dehazing databases, hazy images have been generated using
real haze produced by a professional haze machine. For easy color calibration
and improved assessment of dehazing algorithms, each scene include a MacBeth
color checker. Moreover, since the images are captured in a controlled
environment, both haze-free and hazy images are captured under the same
illumination conditions. This represents an important advantage of the I-HAZE
dataset that allows us to objectively compare the existing image dehazing
techniques using traditional image quality metrics such as PSNR and SSIM
Active Semiconductor Nanophotonics based on Deterministic Quantum Wire and Dot Systems
investigate the use of MOVPE-grown ordered nanostructures on non-planar substrates for quantum nano-photonics and quantum electrodynamics-based applications. The mastering of surface adatom fluxes on patterned GaAs substrates allows for forming nanostrucutres confining well-defined charge carrier states. An example given is the formation of quantum dot (QD) molecules tunneled-coupled by quantum wires (QWRs), in which both electron and hole states are hybridized. In addition, it is shown that the high degree of symmetry of QDs grown on patterned (111) B substrates makes them efficient entangled-photons emitters. Thanks to the optimal control over their position and emission wavelength, the fabricated nanostructures can be efficiently coupled to photonic nano-cavities. Low-threshold, optically pumped QWR laser incorporating photonic crystal (PhC) membrane cavities are demonstrated. Moreover, phonon-mediated coupling of QD exciton states to PhC cavities is observed. This approach should be useful for integrating more complex systems of QWRs and QDs for forming a variety of active nano-photonic structures
Mt. Kelud haze removal using color attenuation prior
Kelud crater observation using closed-circuit television (CCTV) has not been used as the main guide in the world of volcanology. This is caused by observations manually by volcanologist who is not certain and depends on their ability and experience. In practice, there is still obstacles haze in the image taken from CCTV record. This paper present color attenuation prior method to eliminate haze on the digital image. The results obtained showed that the selected method is capable of eliminating sparse haze and moderate haze but not dense haze