Terahertz annular antenna driven with a short intense laser pulse

Abstract

Generation of terahertz radiation by an oscillating discharge, excited by short laser pulses, may be controlled by geometry of the irradiated target. In this work, an annular target with a thin slit is considered as an efficient emitter of secondary radiation when driven by a short intense laser pulse. Under irradiation, a slit works as a diode, which is quickly filled by dense plasmas, closing the circuit for a traveling discharge pulse. Such a diode defines the discharge pulse propagation direction in a closed contour, enabling its multiple passes along the coil. The obtained oscillating charge efficiently generates multi-period quasi-monochromatic terahertz waves with a maximum along the coil axis and controllable characteristics.

Neural network analysis of quasistationary magnetic fields in microcoils driven by short laser pulses

“…For accelerated particle control, same laser pulses may create quasi-stationary electromagnetic structures, with a well controlled magnetic component, created by a closed current circuit in a coil. For potentially interesting big targets, the circuit closure may be controlled by the same laser driver, which is responsible for the excitation of the discharge current, even for very short laser pulses in femtosecond domain 46 . Important conclusion of the presented analysis is that in the short laser pulse regime, the stationary structure formed by electric current with its magnetic field needs an electric connection between the two loop ends .…”

Powerful Elliptically Polarized Terahertz Radiation from Oscillating-Laser-Driven Discharge Surface Currents

“…Note that, there, mainly the collective motion of fast laser-accelerated electrons was considered to be responsible for the THz emission, but the induced surface currents may provide a more-compact and dense radiation source [43]. One of the effective mechanisms for creating such currents involves driving an intense discharge pulse [44][45][46]. For smaller, e.g., sub-picosecond or even femtosecond laser pulses, the degree of localization of this discharge pulse may become sufficiently small on the target scale, and it may emit electromagnetic waves when propagating along a coil-shaped [45] or an undulating [43] wire.…”

“…One of the effective mechanisms for creating such currents involves driving an intense discharge pulse [44][45][46]. For smaller, e.g., sub-picosecond or even femtosecond laser pulses, the degree of localization of this discharge pulse may become sufficiently small on the target scale, and it may emit electromagnetic waves when propagating along a coil-shaped [45] or an undulating [43] wire. Here, we show that a simple solid target with an elliptical outer surface allows obtaining perfectly controlled polarized THz radiation along the normal to the target with the frequency defined by the target perimeter and the degree of ellipticity defined by the ratio of the minor and major axes of the target ellipse.…”

“…As we show below, for an interaction at small angles, the current propagation direction is defined by the irradiation direction, so that it is counterclockwise for the irradiation geometry in a possible experimental setup presented in Figure 1a and clockwise for the 3D simulation geometry in Figure 1b. As the target's outer surface presents a closed loop, no specific conditions are required to close the circuit, which enables the current pulse to make several round turns, as in the case of the coil with a plasma-connected slit [45]. The setup enables the production of multi-period strong waves with perfectly controlled polarization and spectra, which may provide unique possibilities in studies requiring ultrastrong polarized THz radiation.…”

“…The setup enables the production of multi-period strong waves with perfectly controlled polarization and spectra, which may provide unique possibilities in studies requiring ultrastrong polarized THz radiation. In the workflow of the previous experimental [39][40][41][42] and theoretical [35,37,38,43,45] studies aiming at the generation of strong controlled radiation in the THz domain, the work presents a design-theoretical description of the the powerful THz emitter with the possibility of enhanced polarization control, promoting further experimental research of THz sources driven by compact optically induced discharges.…”