The influence of pulse width on relativistic motion and full spatial characteristics of radiation generated from electron oscillations driven by circularly polarized intense femtosecond laser pulses have been investigated theoretically and numerically using a single electron model. The electron trajectories show asymmetric spiral patterns for few-cycle laser pulse which do not resemble with twofold symmetric spiral patterns in the multi-cycle laser pulse. It is discovered that the patterns of the full spatial distribution of electron emission are of the shape resembling a flower of calla for few-cycle laser pulse and the radiated power per unit solid angle show a horn like shape directed toward the direction of the laser pulses propagation with a narrower divergence for multi-cycle laser pulse.
In this paper, based on the Lorentz equation and Maxwell's equations the single electron acceleration model was established, we use MATLAB to study the electron dynamics and radiation emission in the field of a relativistic intense laser pulse. In the spatial distribution of the electron appear "ramifications", and the intensity of electron radiation angle of peak time spectrum showed that, when the beam waist radius from 7λ0 to 4λ0, the main peak change from multiple into a single gradually, from 4λ0 the main peak symmetric bimodal pattern is obvious damage, and the intensity of the main peak is mainly on the left side. The radiation peak is positively correlated with the beam waist radius while the pulse width is just the opposite. Combining with the electronic motion images, we find that the change of the growth trend also occurs at 4λ0 and 7λ0. It marks that, it's possibly that there is an intermediate state between the tight-focused and the non-tight-focused.
This paper demonstrates the influence of pulse width on the full space characteristics of electron motion and radiation distribution from a single electron driven by a linearly polarized femtosecond tightly focused gaussian laser pulse (FTFGLP). The laser-accelerated electron model is created by the interaction between a tightly focused linearly polarized femtosecond gaussian laser pulse and an electron. Driven by the electromagnetic field produced by laser pulse, the electron produces relativistic oscillation and the corresponding full spatial radiation. Through numerical calculation, it is concluded that the space characteristics of relative electron changes firstly and then tends to be stable. In detail, with the increase of plus width, the amplitude of electronic motion tends to a constant value, and there is an optimal value of the change of drift distance that tends to be stable. Moreover, due to the increase of plus width, the phase variation of electron motion in the characteristics of electron space radiation distribution intensifies, and the number of branch gradually increases, but the Angle of the maximum branch is basically unchanged. The characteristics is of great use in some real experiments of linearly polarized laser plus.
Using the theory of single free electron in the form of Thomson scattering, through theoretical calculations and computer simulations, the properties of radiation pulses generated by ultrashort laser pulses are studied. Calculations show that in this case, the pulse width of the electron’s maximum radiation pulse reaches on the order of attosecond. We focus on nonlinear Thomson scattering. Under the condition of circularly polarized tightly focused laser pulses (b0 = 3λ0), we change the intensity of the incident laser. Generally, under the condition of relativistic laser intensity, keep the beam waist radius not changing, the larger the incident laser’s peak amplitude (a0), the larger the maximum of electron radiation power. After that, we focused on the temporal characters at the angle when the electron radiated power was at its maximum. At some special incident laser’s peak amplitude (a0), the change of pulse width in electron radiation power has some rules. We divide the change of pulse width into three categories according to the number of maximal values in the angular distribution of the radiation energy, and discuss the regularity of them separately.
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