Terahertz radiation finds applications in medical science, spectroscopy, security screening, communication, etc. There are several methods that focus on the interaction of lasers with plasma, and laser beating process is an effective scheme for the Terahertz radiation generation. In this scheme, a resonance between the beating frequency and plasma frequency needs to be achieved. In general, only the plasma electrons respond to the lasers field. However, achieving a Terahertz source with variable frequency and power is very difficult, even with the application of an external magnetic field. In this article, we give an analytical analysis of how employing an external magnetic field, a laser-induced transient current in an array of GaAs structures can be used to increase the power of the emitted radiation. The magnetic field has the benefit of not stopping the carriers since these gyrate before they reache the corner, which causes the frequency to affect the current and helps lasting this interaction for a longer time. As a result, 2-3 cycles of the higher frequency pulse are generated, increasing the power by 100 times. پرونده مقاله

Near the critical layer, a p-polarized laser that impinges on a dense plasma having density gradient at an angle to the density gradient transforms into a plasma wave. Even after the laser pulse has stopped, the plasma wave survives. The electrons close to the crucial layer are heated by the plasma wave. Increased plasma pressure and the production of ion-acoustic waves at frequencies lower than those of the ion plasma are the results of a sudden increase in plasma electron temperature. It appears to be a mechanism for ion-acoustic waves observed in an experiment (Adak et al. Phys. Rev. Lett. 114 (2015) 115001), where alternatively the plasma wave can excite ion acoustic waves in Terahertz frequency range via the decay instability. In the present work, we have theoretically demonstrated these observations. پرونده مقاله