Scaling of the terahertz emission from liquid water lines by plasma reshaping

Opt Lett. 2022 Nov 15;47(22):5969-5972. doi: 10.1364/OL.477246.

Abstract

Liquids are proposed to be promising terahertz (THz) sources. However, the detected THz electric field is limited by the collection efficiency and saturation effect. A simplified simulation based on the interference of ponderomotive-force-induced dipoles indicates that, by reshaping the plasma, the THz radiation is concentrated in the collection direction. Experimentally, by using a cylindrical lens pair to form a line-shaped plasma in transverse section, the THz radiation is redirected, and the pump energy dependence follows a quadratic trend, indicating that the saturation effect is significantly weakened. As a result, the detected THz energy is enhanced by a factor of ∼5. This demonstration provides a simple but effective way of further scaling detectable THz signals from liquids.