Terahertz annular antenna driven with a short intense laser pulse

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.