Parameter Analysis of Two-color Laser Sources for Terahertz Wave Radiation from Liquid Water

Liquid water as a source of Terahertz (THz) waves shows better performance than gas medium. In this work, the physical mechanism of THz wave radiation from liquid water excited by two-color laser pulses was investigated by particle-in-cell (PIC) simulation combined with Monte Carlo collision (MCC). The effects of laser parameters including wavelength, relative phase difference and intensity ratio between the fundamental laser and second harmonic on the THz radiation have been analyzed. The flip over of THz field can be obtained by adjusting the relative phase difference. As laser wavelength increases, the intensity of THz radiation keeps increasing. The optimal intensity ratio of fundamental laser and second harmonic for THz generation is approximately 2 : 1.