A5020530238- Semiconductor Quantum Structures and Devices
- Ultrasonics and Acoustic Wave Propagation
- Advanced Semiconductor Detectors and Materials
- Quantum and electron transport phenomena
- Seismic Waves and Analysis
- Acoustic Wave Resonator Technologies
- Laser-Matter Interactions and Applications
- Quantum Dots Synthesis And Properties
- Advanced Fiber Laser Technologies
- Microfluidic and Bio-sensing Technologies
- Mechanical and Optical Resonators
- Thermography and Photoacoustic Techniques
- Strong Light-Matter Interactions
- Spectroscopy and Quantum Chemical Studies
- Chalcogenide Semiconductor Thin Films
- Plasmonic and Surface Plasmon Research
- Spectroscopy and Laser Applications
- Laser Material Processing Techniques
- Photonic Crystals and Applications
- Molecular Junctions and Nanostructures
- Mass Spectrometry Techniques and Applications
- Advanced Fiber Optic Sensors
- Geophysics and Sensor Technology
- ZnO doping and properties
- Thermal Radiation and Cooling Technologies
École Polytechnique
2000-2024
Centre National de la Recherche Scientifique
2007-2024
École Nationale Supérieure de Techniques Avancées
2000-2024
Laboratoire d'Optique Appliquée
2000-2024
Sorbonne Université
2006-2021
Institut des NanoSciences de Paris
2006-2021
Université Paris 1 Panthéon-Sorbonne
2013-2019
Université Paris Cité
2014
IIT@MIT
2011
Inserm
2007
We show experimentally that field-free alignment of iodobenzene molecules, induced by a single, intense, linearly polarized 1.4-ps-long laser pulse, can be strongly enhanced dividing the pulse into two optimally synchronized pulses same duration. For given total energy two-pulse sequence degree is maximized with an intensity ratio 1:3 and sending second near time where created first peaks.
An analytical and numerical approach is developed to pinpoint the optimal experimental conditions irreversibly switch magnetization using surface acoustic waves (SAWs). The layers are magnetized perpendicular plane two switching mechanisms considered. In precessional switching, a small in-plane field initially tilts passage of SAW modifies magnetic anisotropy parameters through inverse magnetostriction. triggers precession and, eventually, reversal. Using micromagnetic fully characterized...
Nonadiabatic laser alignment of an asymmetric top molecule is studied using the combination a quantum dynamical theory and time-resolved photofragment imaging experiments. In particular, degree iodobenzene, induced by intense, linearly polarized picosecond pulse, calculated measured. Pronounced obtained under field-free conditions.
We report a direct determination of the dynamic behavior confined acoustic phonons in nanocavities by picosecond acoustics. provide broadband, high resolution transmission amplitude curve subterahertz range, and we give evidence resonant peaks three successive stop bands, quantitative agreement with simulations. furthermore demonstrate transit times nanosecond range at cavity reflecting strong confinement within layer. On other hand, are measured band, shorter than any constituting...
Abstract As they have gained maturity, colloidal nanocrystals (NCs) also expand the spectral range over of which could be used for photonic and optoelectronic applications. In particular, infrared use NCs has become utmost interest to develop cost‐effective alternatives current technologies. It is then critical not let material dictate light–matter interaction, why coupling cavities been proposed. For NCs, this approach first devoted control absorption with in mind increase signal magnitude...
The rotational revival structure of asymmetric top molecules, following irradiation by an intense picosecond laser pulse, is explored theoretically and experimentally. Numerically we solve nonperturbatively for the dynamics a general subject to linearly polarized analyze dependence dynamical alignment on field system parameters. Experimentally use time-resolved photofragment imaging measure two molecules with different asymmetry, iodobenzene, iodopentafluorobenzene. Our numerical results...
The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer (Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr (MOKE). A transient MOKE signal followed by low amplitude oscillations evidenced, strong dependence applied magnetic field, temperature and ps-ASP amplitude. Careful interferometric measurement the layer's thickness variation induced allowed us to model very accurately resulting signal, interpret it as modulated reflectivity (differing for...
Intraband absorption in doped nanocrystals offers an interesting alternative to narrow-band-gap materials explore mid-infrared optoelectronic device designs. However, the performance of such a clearly lags behind ones relying on intrinsic materials. Livache et al. proposed dye-sensitized approach overcome limitations observed from intraband (high dark current, slow response, low activation energy), where absorber is coupled with undoped material, which takes care charge conduction. Here, we...
Acoustic attenuation rates in vitreous silica the 20–400 GHz frequency range have been measured using a multiple-pulse optical technique for generation of tunable multicycle acoustic waves that are detected interferometrically after traversal sample. The results connect ranges several measurement methods, yielding consistent description behavior.
Dissociation of iodine molecules by two phase-locked 110 femtosecond laser pulses creates a wave packet in the repulsive part $B$ state. The time-dependent density functions for internuclear position, $\ensuremath{\mid}\ensuremath{\Psi}(R,t){\ensuremath{\mid}}^{2}$, and velocity, $\ensuremath{\mid}\ensuremath{\Psi}({v}_{R},t){\ensuremath{\mid}}^{2}$, are measured ionization with delayed, intense $20\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ nonresonant pulse. pronounced interference pattern,...
Nonadiabatic alignment of an asymmetric top molecule induced by a short, moderately intense laser pulse is studied theoretically and experimentally. Numerically, we solve nonperturbatively the time-dependent Schr\"odinger equation for general subject to field, analyze dependence dynamics on field strength rotational temperature. Experimentally, use time-resolved photofragment imaging measure angular distributions spatial orientation molecules. Our studies, using iodobenzene as test molecule,...
Solitons are self-preserving traveling waves of great interest in nonlinear physics, offering many interesting application such as high-bandwidth optical fiber communication. can also appear ultrafast acoustics, and several observations suggest acoustic solitons short 200 fs. Here, the authors designed an experimental setup to observe characterize through a GaAs(001) substrate. The signal is explained well with help Korteweg--de Vries equation, demonstrating particlelike nature unique...
Stimulated photoluminescence of the lower polariton in CdTe microcavities is studied at low temperature, using nonresonant excitation. The stimulation threshold found to be independent number quantum wells microcavities, which rules out model based on population inversion either localized excitons or electron–hole plasma. On other hand, bosonic final state process, boser effect, clearly evidenced by tuning one LO phonon below exciton reservoir. For detunings closer zero, dominated another...
A simple nonradiative Shockley-Read-Hall recombination model is used to interpret transient reflectivity and midinfrared transmission experiments of low-temperature-grown GaAs (LT-GaAs) materials annealed under various conditions temperature duration. The introduces two main parameters, namely the deep-donor (NDD) acceptor (NA) concentrations in matrix, explain all observed behaviors coherently with other results literature. precise study different parameters (pump wavelength power, NDD, NA,...
We present a laser ultrasonics experiment with imaging capabilities performed in transmission through semiconductor substrates. Such provides new kind of bulk wavefront using an ultrafast optical generation and detection scheme for gigahertz waves. The data may be viewed as two-dimensional slices the three-dimensional acoustic revealing basic anisotropy solid 0.3 ps time resolution 3 μm space allowing determination whole set elastic constants various experimental conditions. As examples,...
We report on elasticity measurements in neuronlike cells using picosecond acoustics pump and probe spectroscopy. The stimulated Brillouin oscillations were mapped PC12 to reveal their internal elastic structure. Thanks a Pearson correlation coefficient mapping, different areas could be distinguished. nucleus material shows bulk modulus equal 12.9 GPa the case of dry cell. Attenuation signature gives access dynamical longitudinal viscosity 10.6 mPa ⋅ s, one order magnitude higher than that...
We have observed stimulated scattering in a II-VI microcavity at 80 K under nonresonant excitation conditions. This manifests itself through probe amplification pump-probe reflectivity experiment and highly nonlinear emission an energy corresponding to ${k}_{\ensuremath{\Vert}}\ensuremath{\ne}0$ state on the lower polariton branch. were able follow onset decline of by measuring temporal evolution amplification.
The transient acoustic pulse emitted by a single InAs quantum dots layer was measured depending on the pump wavelength. By tuning wavelength through transition energies of GaAs barrier, wetting and themselves, phonon emission is shown to be strongly correlated electronic structure system. contributions signal were clearly identified quantified comparing different regions same sample containing or not dots.
We report picosecond acoustic measurements of longitudinal sound dispersion and attenuation in an amorphous ${\mathrm{SiO}}_{2}$ layer at temperatures from 20 to 300 K over frequencies ranging about 40 200 GHz. The sample is a radio frequency cathodic sputtered silica grown on sapphire substrate with aluminum film transducer deposited top. Acoustic evaluated the simultaneous analysis three successive echoes using transfer matrix calculation. Results are found follow rather well model...
We have investigated optical properties of high-density InAs self-assembled quantum dots (QDs) in an ${\mathrm{In}}_{x}{\mathrm{Al}}_{1\ensuremath{-}x}\mathrm{As}$ matrix, lattice matched to InP (001) substrate. The weak mismatch $(\ensuremath{\sim}3%)$ results a 90% coverage the surface with QDs. By means interband and intraband spectroscopies crossed atomic force microscopy (AFM) measurements, we determined that QDs depend on deposited amount InAs. Photoinduced absorption spectroscopy has...
We have observed a dynamic saturation of an intersublevel transition in ${\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}/\mathrm{I}\mathrm{n}}_{x}{\mathrm{Al}}_{1\ensuremath{-}x}\mathrm{As}$ quantum dots related to the discrete nature electron states using midinfrared femtosecond spectroscopy. This is consequence gradual filling quantum-dot due capture electrons injected barrier. Our interpretation differential transmission experiments confirmed by comparison with rate-equation model and...