  Metals have been studied as terahertz sources for decades. Recent research
has shown the potential of metals in generating extremely high THz pulse energy
excited by intense laser pulses. To avoid the metal surface debris caused by
laser pulses, here, we report the results of the broadband terahertz wave
emission from a flowing liquid metal line excited by sub-picosecond laser
pulses. The THz signal emitted from the liquid gallium line shows stronger
field with broader bandwidth comparing with the signal from water under the
identical optical excitation conditions. Our preliminary study suggests that
the liquid metals have the potential to serve as efficient and powerful THz
sources for the intense lasers with a high repetition rate.
