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Based on the classical theory of nonlinear Thomson scattering and the single electron model, we performed extensive numerical simulations in MATLAB R2022b to comprehensively investigate how the initial phase of a tightly focused, circularly polarized laser pulse affects the radiation characteristics of high-energy electrons at different energy levels. Our findings indicate that the polar angle corresponding to the maximum radiation energy remains constant as the initial phase of the laser changes from 0 to 2π, while the azimuth angle correspondingly moves from 0 to 2π. Moreover, as the initial phase changes, the pulse width of the electron radiation peak displays a quasi-periodic oscillation with a period of π. Notably, an increase in the initial energy of the electrons results in a significant enhancement in both the peak radiation value and the collimation of the radiation. These results demonstrate that manipulating the initial phase of the driving laser pulse enables effective control over the spatial distribution of radiation light. [ABSTRACT FROM AUTHOR]

In this paper, a model of electron electromagnetic radiation is established using Lorentz formula for the interaction of a tightly focused elliptically polarized laser with a single electron under the condition of nonlinear Thomson scattering. Let the initial pulse width λ 0 be 3.3 fs. By changing the laser pulse width L , the energy distribution and space distribution of electron radiation emitted by electron under different conditions are obtained. The results show that when laser interacts with a single electron, the electromagnetic radiation emitted by the electron accumulates in a cone shape in space. With the increase of pulse width L , the peak energy of electron radiation is bimodal, and the peak power of electron radiation drops. At the same time, the longer it takes for the electron radiation to reach the peak, the frequency spectrum and time function show that the high-frequency component decreases, the cutoff frequency decreases, and the harmonic frequency increases. [ABSTRACT FROM AUTHOR]

Based on the Thomson scattering model of a single high-energy electron interacting with a Gaussian laser pulse, the motion of the electron and the spatial radiation characteristics of the scattered light during the process are simulated with the electron's varying initial position. The results reveal that the initially stationary electron first oscillates, and then travels in a straight line after interacting with a linearly polarized tightly focused intense laser. As the initial position of the electron moves forward on the z axis, the azimuth angle of the maximum energy radiation direction remains unchanged, while the polar angle gradually decreases and finally stabilizes. It is found that the maximum radiated energy in the whole space is obtained only when the electron is initially set at a specific position and when observed from a certain direction. In the maximum energy radiation direction, both the time and the frequency spectra are further studied qualitatively and quantitatively. [ABSTRACT FROM AUTHOR]

Hong et al. [Phys. Plasmas 29, 043102 (2022)] researched the nonlinear Thomson backscatter in a highly focused Gaussian linear laser pulse. They studied the law of backward harmonic spectrum and electron motion trajectory and put forward the view that "the electron will be pushed to the −z-axis by the responsible force of the falling edge of the laser pulse when the interaction time is long enough." In this Comment, we study the electron motion law under the precise laser pulse expression. We find and explain that the initial position of the electron is the reason why the electron is pushed to the −z-axis. Only when the initial position of the electron is in the −z half-axis, the electron will be pushed away at the end of the pulse. [ABSTRACT FROM AUTHOR]

Driven by the electromagnetic field produced by linearly polarized femtosecond laser pulse, the electron’s relativistic oscillation and the corresponding full spatial radiation have been studied theoretically and numerically. The new finding is electron’s radiated power per solid angle by laser pulse with low intensities is almost the same as that produced by a dipole antenna (four-fold rotational symmetry), whereas for the radiation generated by high laser intensities, the radiation takes on two-fold rotational symmetry pattern with further increase of laser intensity. Therefore, this method is of great use in determining the intensity of linearly polarized laser pulses indirectly in real experiment. [ABSTRACT FROM AUTHOR]

Abstract: Relativistic motion and full spatial characteristics of radiation from an electron driven by an intense few-cycle laser pulse have been investigated theoretically and numerically with a single electron model. It is discovered that the influence of the initial phase on the process of relativistic motion and spatial characteristics of the radiation is apparent for intense few-cycle laser pulse. The characteristics can be used to measure the initial phase of intense few-cycle laser pulse in experiment. [Copyright &y& Elsevier]

Abstract: The spatial and spectral characteristics of laser-field synchrotron radiation (LSR) are investigated. The results show that LSR is emitted normal to the laser axis and emission in the X-ray wavelength can be obtained by increasing the intensity of the laser pulse and the initial energy of the electron. The unique feature offered by the laser-field synchrotron radiation (LSR) makes them a promising compact source of light at shorter wavelengths. [Copyright &y& Elsevier]