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Terahertz (THz) waves, as far-infrared light, offer new opportunities for the optical trapping and manipulation of single cells, in contrast to the other light sources. We present an efficient scheme to flexibly control multiple THz field distribution patterns generated by the laser–plasma interaction in a magnetized plasma. An analytical THz radiation field and two-dimensional particle-in-cell simulation are constructed to verify the feasibility of the scheme. Modulation of the THz gradient force and the energy flux by an asymmetrical THz field is investigated for the purpose of trapping and manipulating particles and cells. In particular, the stabilities of flexibly controlled THz radiation are investigated carefully in the form of the strong and short laser and super-strong magnetic field induced significant spatial structure instabilities and frequency instabilities of terahertz radiation. [ABSTRACT FROM AUTHOR]

Propagation of an electromagnetic (EM) pulse in an underdense plasma can either generate a wakefield or excite soliton wave, which depends on the competition between the linear dispersion and nonlinear self-modulation of the wave. Here, we study the interaction of the EM pulse and relativistic hot plasma analytically and numerically and reveal the physical mechanism of the transition from wakefield generation to soliton excitation in terms of soliton stability and modulation instability (MI) of a plane wave. Starting from the relativistic hot fluid-Maxwell model, a nonlinear Schrödinger equation (NLSE) governing the amplitude of scalar potential is obtained by using a multi-scale perturbation technique. The bright and dark soliton solutions of the NLSE are obtained analytically. The stability phase diagram of solitons is given numerically. Furthermore, the MI of the plane wave is studied, and the stability phase diagram of MI is obtained. The results indicate that, when the plasma density increases, the propagation of the EM pulse in the plasma experiences wakefield–soliton transition, which depends on the thermal effect. Our results provide theoretical evidence for deep understanding of high-power laser plasma interaction. [ABSTRACT FROM AUTHOR]

The effects of super-Gaussian chirped laser pulse and inhomogeneity of plasma on space distribution and amplitude of wakefield are studied. The different super-Gaussian chirped laser pulse envelopes are used to strike the uniform and various inhomogeneous plasmas. The results show that compared with the unchirped laser pulse, the chirped laser pulse can enhance the wakefield generation, make the bubbles’ structure deformative seriously, reduce the numbers of bubbles in the same longitudinal distance, and enlarge the size of the wakefield bubbles. Besides, the stronger wakefield is generated in inhomogeneous plasma compared with a uniform one. Moreover, the characteristics of the wakefield can be controlled efficiently by the super-Gaussian pulse index. That is, the amplitude and spatial structure of the plasma wakefield can be modulated by the super-Gaussian chirped laser pulse and the inhomogeneity of the plasma. [ABSTRACT FROM AUTHOR]

The generation of a spatially ultra-compact and high quality terahertz (THz) beam has been a challenging issue at present for advancing the THz technology. Here, we demonstrate an efficient scheme from the laser-plasma interaction in a spatially modulated magnetized plasma to control the THz beam. An analytical THz radiation field and the two-dimensional particle-in-cell simulations based on the scheme are carried out. The spatial distribution, the intensity, and the polarization of the THz beam are highly modulated and controlled by the laser field, external magnetic field, and self-generated plasma channel. A spatially modulated ultra-compact and high-brightness THz beam with the multiple THz field distribution patterns is generated. This scheme opens a practical and economical path to develop the THz technology in various fields. [ABSTRACT FROM AUTHOR]