J. Tignon - Academia.edu (original) (raw)

Papers by J. Tignon

2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2020

Owing to their energy level splitting in the meV range, large graphene quantum dots (size ~100 nm... more Owing to their energy level splitting in the meV range, large graphene quantum dots (size ~100 nm) are very attractive candidates for THz technology. Whereas their electronic properties have been widely studied by transport measurements, only very few works have been focused on their interaction with THz radiation. Here, we report a theoretical and experimental investigation of the optical properties at THz frequencies of large graphene quantum dots. Using a tight-binding modeling, we show the existence of spatially extended mixed-states that should couple efficiently to THz photons. Furthermore, we experimentally demonstrate THz optical absorption of an array of circular 75 nm-diameter graphene quantum dots at 4K and 300K.

2017 42nd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2017

We report saturable absorption in multilayer epitaxial graphene at 4.7 μm wavelength using mid-in... more We report saturable absorption in multilayer epitaxial graphene at 4.7 μm wavelength using mid-infrared quantum cascade laser. From z-scan and differential transmittance measurements, we demonstrate an enhancement of the transmittance of 9 %, attributed to the Pauli blocking effect in the graphene layers. We found that the saturation intensity is in the range of MW/cm2. Our results show the potential of graphene for ultrafast optical modulation in compact mid-infrared platforms as well as for assisting ultrashort pulse generation in quantum cascade lasers.

2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007

The quantum Hall effects (QH) arise in a cold 2D electron gas (2DEG) subject to a perpendicular m... more The quantum Hall effects (QH) arise in a cold 2D electron gas (2DEG) subject to a perpendicular magnetic field. They result from Coulomb correlations among the 2DEG that populates the highly degenerate Landau level (LL) states. Here we study the coherent nonlinear optical ...

Nano Letters, 2014

Nonlinear couplings between photons and electrons in new materials give rise to a wealth of inter... more Nonlinear couplings between photons and electrons in new materials give rise to a wealth of interesting nonlinear phenomena [1]. This includes frequency mixing, optical rectification or nonlinear current generation, which are of particular interest for generating radiation in spectral regions that are difficult to access, such as the terahertz gap. Owing to its specific linear dispersion and high electron mobility at room temperature, graphene is particularly attractive for realizing strong nonlinear effects [2]. However, since graphene is a centrosymmetric material, second-order nonlinearities a priori cancel, which imposes to rely on less attractive third-order nonlinearities [3]. It was nevertheless recently demonstrated that dc-second-order nonlinear currents [4] as well as ultrafast ac-currents [5] can be generated in graphene under optical excitation. The asymmetry is introduced by the excitation at oblique incidence, resulting in the transfer of photon momentum to the electron system, known as the

... ROUSSIGNOL (1) G. BASTARD (1), M. MAAREF (2), V. THIERRY-MIEG(3) and R. PLANEL (3) (1) Labora... more ... ROUSSIGNOL (1) G. BASTARD (1), M. MAAREF (2), V. THIERRY-MIEG(3) and R. PLANEL (3) (1) Laboratoire de Physique de la Mati~re ... We have investigated a set of three [001]-MBE-grown GaAs/Al~Gal_ ~As, nomi-nally 100/~ wide, single shallow quantum wells, with ...

Physica E: Low-dimensional Systems and Nanostructures, 2006

ABSTRACT Using the non linear optical technique of 3-pulse 4-wave mixing, we study the dynamics o... more ABSTRACT Using the non linear optical technique of 3-pulse 4-wave mixing, we study the dynamics of the collective excitations of the quantum Hall system. We excite the system with 100 fs pulses propagating in directions k1 and k3 and then probe its time evolution with a delayed pulse k2. We measure the non-linear optical response from the lowest Landau level along the direction k1+k2−k3. As function of the time delay of pulse k2, this signal shows striking beats for short time delays (∼500 fs), followed by a rise (∼20 ps) and then a decay (∼100 ps). We identify the microscopic origin of this dynamics by extending the standard theory of ultra fast nonlinear optics to include the effects of the correlations.

Physica E: Low-dimensional Systems and Nanostructures, 2003

The polariton nonlinear dynamics in a II-VI semiconductor microcavity has been studied using angl... more The polariton nonlinear dynamics in a II-VI semiconductor microcavity has been studied using angle-resolved four-wave mixing. The low-energy polariton dephasing time is found to decrease at large angles, when polariton can escape towards the excitonic reservoir, in good agreement with a calculation of the angle-dependent collisional broadening. Moreover, we ÿnd that the parametric ampliÿcation of k = 0 polaritons is associated to a strong quenching of the coherence at the magic angle.

Physica E: Low-dimensional Systems and Nanostructures, 2004

The polariton coherent dynamics in the parametric ampliÿcation regime is studied experimentally i... more The polariton coherent dynamics in the parametric ampliÿcation regime is studied experimentally in a II-VI semiconductor microcavity, using angle-resolved four-wave mixing. We observe a strong reduction of the pump polarization dephasing time under excitation at the magic angle above the parametric ampliÿcation threshold. Our observations are analyzed by calculating numerically the coupled rate equations for the signal, pump and idler polariton ÿelds. This allows us to interpret our observations in terms of time-dependent pump depletion. We ÿnd that the coherent dynamics above the threshold is the result of a complex interplay between parametric ampliÿcation and collision broadening.

Comptes Rendus Physique, 2007

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Applied Physics Letters, 2017

The optical spin Hall effect is a transport phenomenon of exciton polaritons in semiconductor mic... more The optical spin Hall effect is a transport phenomenon of exciton polaritons in semiconductor microcavities, caused by the polaritonic spin-orbit interaction, which leads to the formation of spin textures. The control of the optical spin Hall effect via light injection in a double microcavity is demonstrated. Angular rotations of the polarization pattern up to 22 are observed and compared to a simple theoretical model. The device geometry is responsible for the existence of two polariton branches which allows a robust independent control of the polariton spin and hence the polarization state of the emitted light field, a solution technologically relevant for future spin-optronic devices.

We show the coherent detection of the laser emission from seeded terahertz (THz) quantum cascade ... more We show the coherent detection of the laser emission from seeded terahertz (THz) quantum cascade lasers (QCL) with metal-metal waveguides using free-space coupling of a THz pulses to the sub-wavelength waveguide. We implement a simple, monolithic planar horn antenna design on the metal-metal waveguide that reduces the impedance mismatch to the waveguide. The laser emission is seeded and coherently detected using electro-optic sampling. Injection seeding of metal-metal waveguides with a LO phonon depopulation design at liquid nitrogen temperatures is also demonstrated.

Terahertz (THz) time-domain spectroscopy is used to investigate the gain and losses of a THz quan... more Terahertz (THz) time-domain spectroscopy is used to investigate the gain and losses of a THz quantum cascade laser (QCL) operating at 2.86 THz. This measurement technique allows access to the amplitude and phase spectra, allowing the direct determination of the gain. At the emission frequency of the QCL, a value of 6.5 cm-1 is found. The gain can also be studied as a function of different operating conditions, even when no laser action is present. Effects such as gain clamping and spectral narrowing are also observed. Furthermore, temperature measurements illustrate the reduction of the gain as the temperature is increased.

We study the transfer of momentum from photons to dust grains to (molecular) gas in the outflow a... more We study the transfer of momentum from photons to dust grains to (molecular) gas in the outflow around cool giants (carbon-stars, Mira variables and OH/IR stars) beyond the radius where the dust grains condense. The problem is circular: radiation pressure determines the outflow velocity of the dust and thus also the dust density; on the other hand the dust density determines, via radiative transfer effects, the spectrum of the photons and thus the effective radiation pressure. This circular problem is solved by a rapidly converging iterative procedure. We compare our predictions with observed properties of a large sample of OH/IR stars and of Miras and find a good qualitative and quantitative agreement. We confirm a conclusion by Wood et al. (1993) that very luminous OH/IR stars in the Large Magellanic Cloud (LMC) owe their low outflow velocity to the low dust-to-gas ratio, a consequence of the low metallicity of the LMC. Similarly we consider a sample of about 100 OH/IR stars withi...

We report photon-assisted tunneling in a hBN encapsulated graphene quantum dot under coherent THz... more We report photon-assisted tunneling in a hBN encapsulated graphene quantum dot under coherent THz illumination. We demonstrate transport assisted by THz photons within the Coulomb blockade regime. We study the dependence on frequencies and intensity of satellite currents generated by THz illumination. Our study opens promising perspectives for the development of quantum devices and for probing light-matter interaction phenomena.

2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)

2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

Photon-assisted tunneling (PAT) is an attractive process for the study of light-matter interactio... more Photon-assisted tunneling (PAT) is an attractive process for the study of light-matter interaction phenomena. In PAT, the electron tunneling through a quantum dot is enabled via the quantum absorption of an electromagnetic wave. The observation of PAT under THz illumination have been limited to semiconductor superlattices [1] , resonant tunneling diodes [2] and more recently carbon nanotube quantum dots [3] . Graphene quantum dots (GQD) of typical size 100 nm size have great potential for PAT under THz illumination as their energy level splitting to quantum electron confinement falls in the THz range [4] , and room temperature bolometric detection of THz radiation have been demonstrated in GQD-based devices [5] .

Physical Review Applied

We demonstrate mutual synchronization of Josephson oscillations in multiple stacks of intrinsic J... more We demonstrate mutual synchronization of Josephson oscillations in multiple stacks of intrinsic Josephson junctions of the cuprate superconductor Bi 2 Sr 2 CaCu 2 O 8+δ. Detailed analysis of the full polarization parameters allows the determination of a phase correlation between the stacks: a simultaneous emission state is described by a linear combination of individual emission states with a phase retardation. This proves that the stacks are coupled via a Josephson plasma in a superconducting substrate and that the coupling matrices can be extracted from polarization analyses. Our findings suggest a route towards the realization of high-power terahertz sources based on the synchronization of a large number of intrinsic Josephson junctions.

$Research paper thumbnail of Author Correction: Diffraction-limited ultrabroadband terahertz spectroscopy$

Scientific Reports

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Journal of the Optical Society of America B

Exciton polaritons in semiconductor microcavities exhibit many fundamental physical effects, with... more Exciton polaritons in semiconductor microcavities exhibit many fundamental physical effects, with some of them amenable to being controlled by external fields. The polariton transport is affected by the polaritonic spin-orbit interaction, which is caused by the splitting of transverseelectric and transverse-magnetic (TE-TM) modes. This is the basis for a polaritonic Hall effect, called optical spin Hall effect (OSHE), which is related to the formation of spin/polarization textures in momentum space, determining anisotropic ballistic transport, as well as related textures in real space. Owing to Coulombic interactions between the excitonic components of the polaritons, optical excitation of polaritons can affect the OSHE. We present a theoretical analysis of the OSHE and its optical control in semiconductor double microcavities, i.e. two optically coupled cavities, which are particularly well suited for the creation of polaritonic reservoirs that affect the spin-texture-forming polaritons. The theory is formulated in terms of a set of double-cavity spinorpolariton Gross-Pitaevskii equations. Numerical solutions feature, among other things, a controlled rotation of the spin texture in momentum space. The theory also allows for an identification of the effective magnetic field component that determines the optical control in phenomenological pseudo-spin models in terms of exciton interactions and the polariton density in the second lower polariton branch.