Investigation of liquid lines as terahertz emitters under ultrashort optical excitation

TL;DR

This study explores using liquid lines instead of films as terahertz emitters under ultrashort optical pulses, revealing that liquid polarity significantly affects THz generation and enabling potential new THz source development.

Contribution

It introduces liquid lines as a novel geometry for THz emission, demonstrating enhanced signals and the influence of liquid polarity, which was not previously explored.

Findings

Liquid lines boost THz emission compared to films.

Nonpolar liquids like alpha-pinene produce stronger THz signals.

Liquid polarity significantly influences THz wave generation.

Abstract

Recently, there has been growing interest in terahertz (THz) wave generation from liquids under optical excitation. Here, we propose and demonstrate the use of liquid lines in place of liquid films as THz emitters to boost THz signals. The geometry of the emitter eliminates the total internal reflection at the flat liquid-air interface. In addition, we observe that the polarity of the liquid has a significant influence on the THz wave generation. Alpha-pinene, a nonpolar liquid, offers much stronger THz radiation than water does. Besides paving the way to develop intense liquid THz sources, our work indicates that THz waves could be a tool for the further study of laser-liquid interaction.