Search results for "Generation"
showing 10 items of 3050 documents
Harmonic generation from nanorings driven by a two-color laser field
2014
We study the high harmonic generation and the polarization of the harmonics emitted by a nanoring driven by two laser fields of angular frequency ?1 and ?2, with ?2?=?2?1, and ?1 resonant between the ground and the first excited state. We show that by varying parameters, such as laser intensity, photon energy and the delay between the two laser pulses, we can control the number of harmonics and the polarization of the radiation. In particular we show that with this choice of two-laser photon frequency rate we obtain more harmonics with respect to other configurations. We also calculated the average absorbed energy and the average angular momentum acquired by the electron as a function of th…
Laser driven quantum rings: one byte logic gate implementation
2018
We study the effect of the carrier-envelope-phase (CEP) on the high harmonic generation (HHG) from a quantum ring driven by two short orthogonal lasers polarized along the x and y axes. In particular, by varying only the phase of the laser polarized along y it is possible to control the intensity of the emitted harmonics. In fact, we show that the system can efficiently emit harmonics if the laser polarized along y is small and that the cut-off of the spectra can be controlled by changing the phase or the intensity ratio between the two lasers. The wavelet analysis of the emitted harmonics and the time dependence of the angular momentum and of the energy acquired by the electron show that t…
High-order-harmonic generation in dimensionally reduced systems
2013
The time-dependent wave function of a nanoring driven by a laser field is obtained by exploiting the symmetries inherent to the system and used for studying the properties of the electromagnetic radiation emitted by the nanoring as a function of the polarization state of the laser. The diffused radiation has the characteristics of high-order-harmonic generation. For a noncircularly polarized laser field an extension of the expected cutoff position is evident, indicating that nanorings are efficient sources of radiation. The polarization state of the emitted harmonics can be opportunely controlled by varying the parameters of the pump field. The profile of the absorbed angular moment shows t…
Strong field amplification of XUV: phase matching aspects
2011
The dependence of the yield of high-order harmonic generation (HHG) on several important experimental parameters has been successfully modeled in the last 20 years by taking into account the single atom response and propagation effects. We extended this description by adding a stimulated emission process and named it x-ray parametric amplification (XPA). Beyond the super-quadratic increase of the XUV signal, which can be explained only in a limited pressure range by HHG theory, other observed characteristics like exponential growth, gain narrowing, strong blue-shift, beam divergence, etc. and their dependence on laser intensity and gas pressure can be explained accurately only by the new XP…
Classical chaos and harmonic generation in laser driven nanorings
2016
A quantum ring driven by an intense laser field emits light in the form of high-harmonic radiation resulting from the strong acceleration experienced by the active electrons forced to move on a curved trajectory. The spectrum of the emitted light is rich and strongly dependent on the parameters of the problem. In order to investigate the physical origin of such variability, we focus on the seemingly simple problem of a laser-driven charge constrained to a ring from a classical standpoint. As it turns out, the dynamics of such a classical electron is governed by a nonlinear equation which results into a chaotic motion - by nature depending on the initial conditions in an unpredictable way. O…
Analyzing dynamical gluon mass generation
2007
We study the necessary conditions for obtaining infrared finite solutions from the Schwinger-Dyson equation governing the dynamics of the gluon propagator. The equation in question is set up in the Feynman gauge of the background field method, thus capturing a number of desirable features. Most notably, and in contradistinction to the standard formulation, the gluon self-energy is transverse order-by-order in the dressed loop expansion, and separately for gluonic and ghost contributions. Various subtle field-theoretic issues, such as renormalization group invariance and regularization of quadratic divergences, are briefly addressed. The infrared and ultraviolet properties of the obtained so…
Study of Mode Competition in the Third Harmonic Gyrotron with Inclusion of the Electron Velocity Spread and the Beam Width
2018
Influence of the electron velocity spread and the beam width on the mode competition and efficiency is investigated in the 1.185- THz third harmonic gyrotron to be used in dynamical nuclear polarization - nuclear magnetic resonance (DNP-NMR) spectrometer.
Bloch wave theory of modulational polarization instabilities in birefringent optical fibers
1997
The modulational instability gain spectra, of an arbitrarily polarized intense pump wave that experiences periodic nonlinear polarization rotation in a birefringent optical fiber, are derived by Floquet analysis. The predictions of the linearized analysis are confirmed by numerical simulations of the coupled nonlinear Schr\"odinger equations.
Modulational instability processes in optical isotropic fibers under dual- frequency circular polarization pumping
2002
Experiments are presented showing that, under dual-frequency, circular polarization pumping, host modulational instability processes can be generated in a single-mode isotropic fiber by careful tuning of the frequency spacing between the pumps.
Plasma emission at the laser tripled frequency
2003
The third harmonic generation in the skin-layer of a dense hot plasma due to inverse bremsstrahlung is investigated for regimes having increasing experimental relevance. New analytical dependencies of the radiation flux density at the frequency 3ω on the plasma and fundamental wave parameters are established.