A5114084901- Geometric and Algebraic Topology
- Homotopy and Cohomology in Algebraic Topology
- Advanced Combinatorial Mathematics
- Terahertz technology and applications
- Advanced Numerical Analysis Techniques
- Computational Geometry and Mesh Generation
- Photonic and Optical Devices
- Algebraic structures and combinatorial models
- Superconducting and THz Device Technology
- semigroups and automata theory
- Topological and Geometric Data Analysis
- Algebraic Geometry and Number Theory
- Spectroscopy and Laser Applications
- Geometric Analysis and Curvature Flows
- Algorithms and Data Compression
- Artificial Immune Systems Applications
- Advanced Differential Equations and Dynamical Systems
- Thermal Radiation and Cooling Technologies
- Advanced Operator Algebra Research
- Advanced MEMS and NEMS Technologies
- Mechanical and Optical Resonators
- Advanced Chemical Sensor Technologies
- Advanced Semiconductor Detectors and Materials
- Mathematical Dynamics and Fractals
- Dynamics and Control of Mechanical Systems
Institut Fourier
2015-2024
Université Grenoble Alpes
2013-2024
CEA Grenoble
2015-2022
Institut polytechnique de Grenoble
2012-2022
CEA LETI
2008-2022
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2009-2022
Centre National de la Recherche Scientifique
2003-2013
Kyoto University
2004-2008
Aarhus University
2005-2008
Laboratoire de Mathématiques Jean Leray
2002-2005
Abstract The reduced peripheral system was introduced by Milnor [18] in the 1950s for study of links up to link-homotopy, that is, homotopies leaving distinct components disjoint; this invariant, however, fails classify link-homotopy four or more components. purpose paper is show topological information which detected Milnor’s actually 4-dimensional. main result gives indeed a complete characterization having same system, terms ribbon solid tori 4–space link-homotopy. proof relies on an...
teaching and research institutions in France or abroad, from public private centers.L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques niveau recherche, publiés ou non, émanant des établissements d'enseignement recherche français étrangers, laboratoires publics privés.
Terahertz uncooled antenna-coupled microbolometer focal plane arrays are being developed at CEA-LETI for THz imaging and sensing. This detector technology relies on amorphous silicon bolometer know-how aims opening the way to real-time video rate 2D imaging, with potential low cost either in fabrication operation. First prototypes of 320x240 pixel have been designed 1-3 Sensors fabricated monolithically above CMOS Integrated Circuits while applying only full Si standard processes. We present...
Let $\Sigma$ be a compact oriented surface of genus $g$ with one boundary component. Homology cylinders over form monoid $\mathcal {IC}$ into which the Torelli group {I}$ embeds by mapping cylinder construction. Two homology $M$ and $Mâ$ are said to $Y_k$-equivalent if is obtained from âtwistingâ an arbitrary $S\subset M$ homeomorphism belonging $k$-th term lower central series $S$. The $J_k$-equivalence relation on defined in similar way using Johnson filtration. In this paper, we...
Spectral signatures of solid materials in the THz range can provide spectroscopic information for chemical identification. Previously we have demonstrated absorption coefficient extraction by scanned imaging QCL beams attenuated through explosive samples. The detection was achieved a unique pixel addressed within an uncooled antenna-coupled microbolometer 160x120 array specifically designed 1-5 range. This detector technology developed at CEA-LETI relies on amorphous silicon bolometer...
We consider local moves on classical and welded diagrams: (self-)crossing change, (self-)virtualization, virtual conjugation, Delta, fused, band-pass, band-pass moves. Interrelationships between these are discussed, and, for each of moves, we provide an algebraic classification. address the question relevant extensions in sense that quotient object embeds into objects. As a byproduct, obtain all mentioned unknotting operations (long) knots. also mention some topological interpretations...
We consider several classes of knotted objects, namely usual, virtual and welded pure braids string links, two equivalence relations on those induced by either self-crossing changes or self-virtualizations. provide a number results which point out the differences between these various notions. The proofs are mainly based techniques Gauss diagram formulae.
Portability, low cost and fast acquisition rates are key features that a THz imaging system should satisfy for extended commercialized applications. With regards to these features, the source - detector association of Quantum Cascade Laser (QCL) with an un-cooled micro-bolometer two-dimensional array looks promising active imaging. QCLs performance is rapidly improving, higher operating temperatures output powers recently demonstrated. On side, opens way real-time video rate, no raster...
For Σ a compact connected oriented surface, we consider homology cylinders over Σ: these are cobordisms with an extra homological triviality condition. When considered up to Y 2 -equivalence, which is surgery equivalence relation arising from the Goussarov-Habiro theory, form Abelian group. In this paper, when has one or zero boundary component, define map certain space of graphs This shown be isomorphism, inverse given by some extensions first Johnson homomorphism and Birman-Craggs homomorphisms.
We show that the Casson knot invariant, linking number and Milnor's triple number, together with a certain 2-string link invariant $V_2$, are necessary sufficient to express any string Vassiliev of order two. Explicit combinatorial formulas given for these invariants. This result is applied theory claspers links.
A link L in the 3-sphere is called Brunnian if every proper sublink of trivial. In a previous paper, Habiro proved that restriction to links any Goussarov–Vassiliev finite type invariant (n + 1)-component degree < 2n The purpose this paper study first nontrivial case. We show an can be expressed as quadratic form on Milnor link-homotopy invariants length n 1.
The European Space Agency (ESA) has committed to a multi-spacecraft Cornerstone mission the planet Mercury. BepiColombo comprises two spacecraft, one of which (The Mercury Planetary Orbiter platform (MPO)) will contain remote sensing instruments for making measurements at wavelengths from far infrared γ-rays. MERcury Thermal Infrared Spectrometer (MERTIS) measures spectral emittance in range 7 14 μm derive surface mineralogy. It employ an uncooled IR focal plane array (IRFPA) heart...
In this paper, we give a complete set of finite type string link invariants degree <5. addition to Milnor invariants, these include several constructed by evaluating knot on certain closure (cabled) links. We show that classify links up C_k-moves for k<6, which proves, at low degree, conjecture due Goussarov and Habiro. also similar characterization concordance <6.
Antenna coupled bolometers developed at CEA-Leti can address the whole THz range by proper tailoring of antennas while keeping technological stack unchanged. This paper presents flexibility design regarding absorption frequency and its capability to sense frequencies below 1 THz.
We consider surgery moves along .nC 1/-component Brunnian links in compact connected oriented 3-manifolds, where the framing of components is f 1 k ; 2 Zg.We show that no finite type invariant degree < 2n can detect such a move.The case two link-homotopic also considered.We relate invariants integral homology spheres obtained by operations to Goussarov-Vassiliev links.
The universal sl_2 invariant of string links has a universality property for the colored Jones polynomial links, and takes values in h-adic completed tensor powers quantized enveloping algebra sl_2. In this paper, we exhibit explicit relationships between Milnor invariants, which are classical invariants generalizing linking number, providing some new topological insight into quantum invariants. More precisely, define reduction invariant, show how it is captured by concordance We also...
CEA-Leti has developed a real-time reflection imaging system: it combines illumination by QCL sources and telescope that focuses the reflected radiation onto camera houses an uncooled 320×240 antenna-coupled micro-bolometer array driven FPGA card. We present first high resolution images of illuminated surfaces acquired in real-time.
Uncooled antenna-coupled microbolometer focal plane arrays have been specifically tailored for optimum performance in the 1-5 Terahertz range. A prototyping batch of 160 × 120 pixel chips has designed and then processed above 8" silicon substrates. An actively illuminated system experimentally tested where Quantum Cascade Lasers (QCLs) are associated with room-temperature operating 2D sensor. Whereas explosives samples were introduced THz beam optical path, profile modified sensed by a...
The purpose of the paper is twofold.First, we give a short proof using Kontsevich integral for fact that restriction an invariant degree 2n to .nC1/componentBrunnian links can be expressed as quadratic form on Milnor x link-homotopy invariants length n C 1. Second, describe structure Brunnian part degree-2n graded quotient Goussarov-Vassiliev filtration .nC1/-componentlinks.
CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists silicon microbolometer coupled to specific antennas and resonant quarter-wavelength cavity. First prototypes of arrays have been designed manufactured sensing 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP order 1 pW/sqrt(Hz) assessed at 2.5 THz. This paper reports steps this development,...
Terahertz uncooled antenna-coupled microbolometer focal plane arrays are being developed at CEA Leti for real time THz imaging and sensing. This detector relies on LETI amorphous silicon infrared bolometer technology that has been deeply modified to optimize sensitivity in the range. The main technological key lock of pixel structure is quarter wavelength cavity consists a thick dielectric layer deposited over metalized CMOS wafer; such improves significantly optical coupling efficiency....
The intrinsic performance of the antenna-coupled bolometer array developed at CEA-LETI was hampered by noise readout chain. Recent improvements camera electronics have made possible optimization sensor operation in bias and integration time. It results a real-time uncooled imager with sensor-limited minimum detectable power that is improved factor 3, i.e. close to 10 pW, 2.5 THz.