Search results for " Harmonic Generation"
showing 10 items of 100 documents
Quantum Ring in a Magnetic Field: High Harmonic Generation and NOT Logic Gate
2020
The effect of a static magnetic field on the high harmonic generation (HHG) from a quantum ring driven by one laser polarized along the x-axis is studied. The spin polarization (Formula presented.) and the temporal emission of the harmonics are studied by varying the intensity of the magnetic field and it is shown how these results have a significant technological impact in computer technology; in fact a boolean algebra can be implemented by assigning 0 and 1 values to low and high pulse intensities of the emitted harmonics and logic gates like the NOT can be created.
Thermalization and condensation in an incoherently pumped passive optical cavity
2011
International audience; We study theoretically and numerically the condensation and the thermalization of classical optical waves in an incoherently pumped passive Kerr cavity. We show that the dynamics of the cavity exhibits a turbulent behavior that can be described by the wave turbulence theory. A mean-field kinetic equation is derived, which reveals that, in its high finesse regime, the cavity behaves essentially as a conservative Hamiltonian system. In particular, the intracavity turbulent field is shown to relax adiabatically toward a thermodynamic equilibrium state of energy equipartition. As a consequence of this effect of wave thermalization, the incoherent optical field undergoes …
Intense, table-top, sub-fs radiation sources. Current status and future perspectives
2008
Talk given by D. Charalambidis; International audience
The influence of the quantum nature of nuclei in high harmonic generation from H$_2^+$-like molecular ions
2013
We study the full quantum dynamics of a simple molecular ion driven by an intense laser field. In particular we show that the quantum nature of the nuclear dynamics affects the emitted high harmonic generation (HHG) spectra, strongly reshaping the plateau region. In fact, it is evident that the characteristic flat trend is transformed into a descending trend, with the lower harmonics being two orders of magnitude more intense than the higher harmonics. We show that this effect is more pronounced in the lighter isotopic species of H$_2^+$ molecular ions and we also demonstrate that in this case the contribution to HHG from the antibonding electronic energetic surface is of the same order of …
Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction
2011
The self-assembly of the oppositely charged water-soluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP(4+)) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS(4-)), at the interface with an organic solvent to form molecular "rafts", provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found to be as good as that of the Pacman type cofacial cobalt porphyrins. The assembly has been characterized by UV-visible spectroscopy, Surface Second Harmonic Generation, and Scanning …
Second order nonlinear optics in AlGaAs metasurfaces
2023
Recently, nonlinear optics at the nanoscale level has emerged as a promising branch of nanophotonics. In this work, we focus our attention on Aluminum Gallium Arsenide (AlGaAs) nanoantennas and metasurfaces for efficient and controlled second harmonic photon emission. After a brief introduction concerning the main studies in this field, we present the latest results achieved in AlGaAs platforms both in the lossless and absorption regimes.
Second Harmonic Emission From Dielectric Nanoresonators in the Absorption Regime
2023
We study second harmonic generation in dielectric nanocylinders as a function of the wavelength of the incident field and geometrical dimensions. Uncommonly, we consider a spectral range in which the emitted nonlinear signal is partially absorbed by the dielectric. Surprisingly, we reveal that the second harmonic efficiency does not decrease as the imaginary part of the complex dielectric refractive index increases. Indeed, the presence of higher order multipoles supported by the resonators at the fundamental wavelength can significantly boost the generated second harmonic signal even in the dielectric absorption spectral region achieving nonlinear efficiency of the same order of magnitude …
Nanorings driven by a laser field
2013
We present the dynamics of an electron constrained over an 1D ring with radius of 0.142 nm driven by a laser field. The temporal evolution of the system is evaluated by a semi-analytical solution of the full quantum time dependent Schr¨odinger equation. In our calculation the gap energy between the ground and the first excited state of the nanoring is three times the photon energy laser (0.63 eV) and the laser intensity is 4·1014 W/cm2 . Our analysis is performed by considering different polarization states of the incident laser. Our attention is mainly focused on the study of the High Harmonic Generation (HHG), the energy and the angular momentum absorbed by the driven system. We observe 1…
Quasi Phase Matched UV Second Harmonic Generation in Lithium Tantalate soft PE Waveguides
2008
We report on first experimental results on UltraViolet second-harmonic generation by first-order quasiphase-matching in a surface periodically poled proton exchanged Lithium Tantalate waveguide. We have achieved a good compatibility with alpha phase proton exchanged channel waveguides in Lithium Tantalate. We held the sample in a temperature controlled oven kept at a constant temperature of 250 °C, to reduce photorefractive damage. The pump source was a Ti-Sapphire laser with a tunability range of 700 - 980 nm and a 40-GHz linewidth. Continuous wave UV light at 365.4 nm was produced with a conversion efficiency of 6.6% W-1cm-2.
Realization of time-resolved two-vacuum-ultraviolet-photon ionization
2009
International audience; Ultrafast dynamics of excited molecules is studied through time-resolved two-vacuum-ultraviolet (vuv)- photon ionization using a nonlinear volume autocorrelator unit. The two-vuv-photon process is induced by the intense fifth harmonic radiation of a femtosecond Ti:sapphire laser. In a proof-of-principle experiment, ultrafast dynamics of excited ethylene and oxygen molecules are investigated. Molecular decay times are deduced by comparing the experimental data with the results of a numerical model that accounts for the spatial and temporal characteristics of the harmonic field. The present experiments pave a convenient way for time domain investigations in the vuv-xuv s…