Terahertz radiation induced by shift currents in liquids

Area of Science:

• Physics
• Physical Chemistry
• Optics

Background:

• Laser-induced terahertz (THz) radiation in liquids exhibits unique properties distinct from gas and plasma sources.
• Efficient production via monochromatic lasers, maximized yield with longer pulse durations, and linear dependence on excitation energy are key features.
• Disordered liquid structures complicate the understanding of ultrafast dynamics underlying THz generation.

Purpose of the Study:

• To elucidate the microscopic mechanism behind laser-induced THz radiation in bulk liquids.
• To propose a theoretical model that explains observed experimental phenomena.
• To provide a framework for investigating nuclear quantum effects in THz generation.

Main Methods:

• Development of a novel shift-current model.
• Theoretical analysis of ultrafast dynamics in liquids.
• Comparison of theoretical predictions with experimental observations of THz radiation.

Main Results:

• The proposed shift-current model successfully reproduces experimental observations of liquid THz radiation.
• The model explains the distinct behavior of unmodulated THz fields in two-color laser fields.
• The theory provides a foundation for exploring nuclear quantum effects in H2O and D2O THz generation.

Conclusions:

• The shift-current model offers fundamental insights into the origin of THz radiation in bulk liquids.
• This theoretical advancement aids in understanding complex ultrafast dynamics in disordered media.
• The model paves the way for future investigations into quantum effects influencing THz production.