A5007259477- Optical Wireless Communication Technologies
- GaN-based semiconductor devices and materials
- Adaptive optics and wavefront sensing
- Semiconductor Quantum Structures and Devices
- Astronomy and Astrophysical Research
- ZnO doping and properties
- Optical Network Technologies
- Stellar, planetary, and galactic studies
- Photonic and Optical Devices
- Advanced Frequency and Time Standards
- Quantum Information and Cryptography
- Ga2O3 and related materials
- Atomic and Subatomic Physics Research
- Satellite Communication Systems
- Advanced Optical Network Technologies
- Advanced Photonic Communication Systems
- Semiconductor Lasers and Optical Devices
- Acoustic Wave Resonator Technologies
- Orbital Angular Momentum in Optics
- Spectroscopy and Laser Applications
- Optical Systems and Laser Technology
- Nanowire Synthesis and Applications
- Advanced optical system design
- Semiconductor materials and devices
- Thermal Radiation and Cooling Technologies
Defence Science and Technology Agency
2024
Office National d'Études et de Recherches Aérospatiales
2019-2024
Université Paris-Saclay
2018-2024
Observatoire de Paris
2023-2024
Systèmes de Référence Temps-Espace
2023-2024
Sorbonne Université
2023
Centre National de la Recherche Scientifique
2020-2023
Thales (France)
2021
Université Paris Sciences et Lettres
2020
Galaxies, Etoiles, Physique et Instrumentation
2020
Free-space optical (FSO) communication technologies constitute a solution to cope with the bandwidth demand of future satellite-ground networks. They may overcome RF bottleneck and attain data rates in order Tbit/s only handful ground stations. Here, we demonstrate single-carrier line-rate transmission over free-space channel 53.42 km between Jungfraujoch mountain top (3700 m) Swiss Alps Zimmerwald Observatory (895 near city Bern, achieving net-rates up 0.94 Tbit/s. With this scenario feeder...
Abstract Future quantum communication infrastructures will rely on both terrestrial and space-based links integrating high-performance optical systems engineered for this purpose. In downlinks in particular, the loss budget variations signal propagation due to atmospheric turbulence effects impose a careful optimization of coupling light single-mode fibers required interfacing with receiving stations ground networks. work, we perform comprehensive study role adaptive optics (AO)...
Optical technologies are extremely competitive candidates to achieve very-high throughput links between ground and GEO satellites; however, their feasibility relies on the ability mitigate channel impairments due atmospheric turbulence. For that purpose, Adaptive Optics (AO) has already proved be highly efficient downlink. However, for uplink, anisoplanatism induced by point-ahead angle (PAA) compromises AO pre-compensation efficiency an extent depends propagation conditions. The properly...
This paper assesses intersubband (ISB) transitions in the 1–10 THz frequency range nonpolar m-plane GaN/AlGaN multi-quantum-wells deposited on free-standing semi-insulating GaN substrates. The quantum wells (QWs) were designed to contain two confined electronic levels, decoupled from neighboring wells. Structural analysis reveals flat and regular QWs perpendicular in-plane directions, with high-angle annular dark-field scanning transmission electron microscopy images showing inhomogeneities...
In this paper, we study band-to-band and intersubband characteristics of GaN/AlN heterostructures (planar nanowires) structurally designed to absorb in the short-wavelength infrared region, particularly at 1.55 microns. We compare effect doping GaN sections with Si Ge, discuss variation free-carrier screening density well/nanodisk size. observe that nanowire consistently present longer photoluminescence decay times than their planar counterparts, which supports existence an in-plane...
We present a study of germanium as n-type dopant in wurtzite GaN films grown by plasma-assisted molecular beam epitaxy, reaching carrier concentrations up to 6.7E20 cm-3 at 300K, well beyond the Mott density. The Ge concentration and free density were found scale linearly with flux studied range. All GaN:Ge layers smooth surface morphology atomic terraces, without trace pits or cracks, mosaicity samples has no noticeable dependence on concentration. variation band gap is consistent...
To concurrently cope with the scarcity of RF frequency bands, growing capacity demand and required lower cost ground segment, Very High Throughput Satellites systems must rely on new technical solutions. Optical feeder links are considered as a promising alternative to surpass classical technology, offering assets inherent optical technologies (large bandwidth, no regulation, low beam divergence, components availability). Nevertheless potential this technology shall not conceal remaining...
This paper assesses nonpolar m- and a-plane GaN/Al(Ga)N multi-quantum-wells grown on bulk GaN for intersubband optoelectronics in the short- mid-wavelength infrared ranges. The characterization results are compared to those reference samples polar c-plane, verified by self-consistent Schr\"odinger-Poisson calculations. best terms of mosaicity, surface roughness, photoluminescence linewidth intensity, as well absorption obtained from m-plane structures, which display room-temperature range...
This paper assesses the effects of Si doping on properties nonpolar m-plane GaN/AlGaN quantum wells (QWs) designed for intersubband (ISB) absorption in far-infrared spectral range. For levels up to 3 × 1012 cm−2, structural analysis reveals uniform QWs with abrupt interfaces and no epitaxially induced defects. Cathodoluminescence spectroscopy confirms homogeneity multiple along growth direction. Increasing density from 1 1011 cm−2 induces a broadening photoluminescence as well reduction...
Free-space optical satellite-earth links often operate at the SNR limit. We show that under low conditions it is more favorable to higher speeds with lower order modulation formats. This follows from Shannon capacity limit formula where transmission bandwidth has a linear impact, whereas logarithmic effect. In practice, limitations hardware need be considered making maximization joint optimization. Here we experimentally substantiate these findings by e.g., comparing two 128 Gbit/s signals -...
GaN/AlN nanowire heterostructures can display photoluminescence (PL) decay times on the order of microseconds that persist up to room temperature. Doping GaN nanodisk insertions with Ge reduce these PL by two orders magnitude. These phenomena are explained three-dimensional electric field distribution within nanodisks, which has an axial component in range a few MV/cm associated spontaneous and piezoelectric polarization, radial contribution shear components lattice strain. At low dopant...
Space data highway networks are currently being deployed to provide high rate connectivity non-fibre-connected areas around the world and prepare incoming growth of Internet Of Things market. Among other solutions, GEO optical feeder links seen as backbone future globalized very satellite-based telecommunication networks. The FEEDELIO experiment developed for ESA in April 2019 demonstrated relevance angular decorrelation models assess statistical characteristics pre-compensated uplink...
GaN/AlN is a promising material system for the development of an ultrafast intersubband technology operating at telecommunication wavelengths, thanks to large conduction band offset and sub‐picosecond intraband relaxation time. In this paper, we explore short wavelength infrared transitions occurring in heterostructures both planar nanowire (NW) geometries. We study effect Si Ge doping quantum wells NW using same active region thickness dopant concentration. demonstrate that are suitable...
The future of very high throughput optical links between the ground and GEO satellites depends on ability to overcome turbulence channel disruptions caused by propagation through atmosphere. Pre-compensation adaptive optics has been identified as a game changer, it could theoretically provide for uplink additional margin necessary secure link budget. Several experimental activities have reported investigate practical increase that can be expected from AO pre-compensation, demonstrating...
In this paper, we study the adsorption/desorption kinetics of gallium on (1-100) m-GaN during molecular-beam epitaxy bulk substrates. We demonstrate stabilization a laterally contracted biatomic layer Ga containing up to ≈2.5 times (0001) surface atom density, top GaN(1-100) surface. By assessing morphology layers grown under different Ga/N flux ratios, show that presence bilayer allows growth atomically smooth without accumulation droplets and in conditions (substrate temperature ratio) are...
Adaptive-Optics (AO) pre-compensation of atmospheric turbulence effects is one the most promising technologies for achieving very high throughput optical GEO feeder links. However, its great performance has been proven mostly through numerical simulations until now, and experimental work on subject still at a preliminary stage [1]. The FEEDELIO experiment (FEEDELIO FEEDEr Link adaptive Optics), contracted to ONERA by ESA described in this paper, goes step further towards an validation...
Optical feeder links (OFL) are expected to become part of future Very High Throughput Satellite (VHTS) systems in response the growing demand for higher capacity and lower costs. H2020 VERTIGO (Very Ground Link) project was set prove key optical communication technologies address: 1) increase with high spectral power efficiencies. 2) Higher generation delivery. 3) Atmospheric turbulence mitigation by digital processing. Transmit receive models were developed rack units assessing, laboratory...
Abstract We present the development and current status of REFIMEVE national research infrastructure, which disseminates time frequency reference signals generated at LNE-SYRTE to labs all over France. Using mainly optical fiber backbone RENATER, French National Research Education Network, currently provides an around 15 labs, connection points Germany, UK, Italy Switzerland. The robustness various types equipment specifically developed for transfer ultrastable frequencies efficient...
Abstract In electrochemical sensing devices, aimed for acute and chronic in vivo application, the active surface of sensor is often negligible compared to overall area device contact with biological host. Consequently, minimize perturbation an implanted on environment chemical composition texturing complete (the sensor, substrate, “accessories”) have be considered. our work, adsorption three abundant proteins (albumin, IgG, fibrinogen) was determined quantitatively untreated modified...
We demonstrate intersubband polaritons in the short-infrared wavelength range (λ < 3 μm) relying on GaN/AlN semiconductor system. The demonstration is given for an transition centered at λ = 3.07 μm (E 403 meV). polaritonic dispersion measured room temperature: a Rabi energy of 53 meV (i.e., minimum splitting 106 meV), which represents 13.1% bare transition, demonstrated. A metal-insulator-metal resonator architecture employed, proves to be efficient even these short wavelengths.
The need for space-ground data transmission systems with high throughput has encouraged the development of new satellite-to-ground laser links, using adaptive optics to compensate deleterious effects atmospheric turbulence. On ground segment, use single-mode fiber components, and thus coupling propagating signal into a fiber, is strongly favored. However, efficiency resulting rate are hampered by turbulence-induced phase distortions amplitude fluctuations (called "scintillation")....