ИСТИНА

Terahertz pulsed radiation is a highly desired tool for biomedical application, molecular spectroscopy, remote sensing and time-resolved studies of ultrafast charge-carrier dynamics in metals and semiconductors [1]. Thin-foil irradiation by high intensity laser pulses is considered as one of the most promising mechanism of high-yield THz generation. In this work we experimentally investigate efficiency of THz generation by 1-10 terawatt Ti:Sa laser pulses irradiating foils of different thickness on the order of few tens of microns as well as solid surfaces of thick dielectric plates (Fig. 1). THz pulses with energy up to 10 J are observed. High-power microwaves are also detected as a low-frequency part of transition radiation (TR) emitted by relativistic electrons traversing vacuum-plasma boundary [2,3]. We have also observed week THz signal from a surface of a BK7 glass plate irradiated by sub-relativistic intensity I  6x1016 W/cm2 pulses (a0 0.8) at the central wavelength of = 3.9 m delivered by an OPCPA mid-infrared laser system. The same level of THz radiation is observed with the Ti:Sa system at intensity I  1x1018 (a0 0.8) in correspondence with I002 scaling [3].