Broadband terahertz wave emission from liquid metal

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 subpicosecond laser pulses. The THz signal emitted from the liquid gallium line shows the stronger field with the broader bandwidth compared to 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.