Sideway terahertz emission from a flowing water line

Plasma-based terahertz wave photonics in gas and liquid phases

“…A similar trend can be observed in the experiment using the 0.21-mm-diameter water line [136] . Figure 55(a) shows the overall variation of the THz waveform when the water line moves along the x axis in a 2D manner.…”

“…57(b)-57(e), one can see that the radiation energy is concentrated more in the direction along the x axis as the length of the dipole array (i.e., number of dipoles) increases. This result implies that the THz radiation generated from plasma in water with a line-like transverse section can be coupled out of [136] . Figures reprinted with permission from Ref.…”

“…However, even at the optimal incident angle, most of the THz energy cannot be coupled out of the water film due to the total internal reflection at the water–air interface and the absorption of water [127] . In contrast, the water line scheme can significantly reduce the total internal reflection owing to its cylindrical water–air interface, and enables the investigation into the sideway emission of THz radiation [134,136] . Thus, in the case of the water line scheme, the full angular distribution of THz radiation from laser-induced plasma in liquid water can be experimentally revealed.…”

“…It has been proved that the lateral detection scheme is more efficient than the forward scheme [ 134 , 136 ] . It is necessary to introduce the impact of the relative position between the water line and the laser axis on THz wave collection efficiency for the lateral scheme.…”

“…The color bar represents the THz wave amplitude. Corresponding THz energy dependence on (b) x-and (d) z-positions of water line[136] . Figures reprinted with permission from Ref [136],.…”