研发大功率、高能量、高效率且能在室温下稳定运行的太赫兹辐射源是太赫兹技术领域迫切需要解决的实际问题。基于瞬态光电流模型, 采用数值仿真方法研究了三色激光脉冲诱导液体介质产生太赫兹波的物理过程, 分析了相位差、强度比、波长以及脉宽对太赫兹辐射的影响。仿真结果表明: 二次谐波和三次谐波相对于基波的相位差、强度比、波长、脉宽等都对太赫兹电场有明显的影响。同时, 只有电离率随着激光电场振荡变化的隧穿电离机制才能产生瞬态光电流, 从而得到太赫兹辐射。

The development of high-power, high-energy, high-efficiency terahertz radiation sources that can operate stably at room temperature is a practical problem that urgently needs to be solved in the field of terahertz technology. Based on the transient photocurrent model, this paper studied the physical process of three-color laser pulse-induced terahertz waves in liquid media by numerical simulations, and analyzed the effects of phase difference, intensity ratio, wavelength, and pulse width on the terahertz radiation. The simulation results show that the phase differences, the intensity ratios, the wavelength and the pulse width have obvious effects on the terahertz electric field. At the same time, only the tunnel ionization mechanism in which the ionization rate changes with the oscillation of the laser electric field can generate transient photocurrents, thereby obtaining terahertz radiation.