在短丝条件下, 激光与喷气靶产生的介质相互作用, 可产生局部高密度等离子体, 在较短距离内实现双色场相位差的剧烈变化, 容易得到椭圆偏振的太赫兹(THz)辐射。通过调节气体背压, 产生了椭偏度为0.438的THz辐射。利用瞬态光电流模型对实验结果进行模拟, 所得结果和实验结果基本一致, 揭示了光电流和等离子体色散共同作用的机理。

Under short filament condition, the plasma with locally high density can be generated by means of the interaction between laser and medium from jet target, the acute change of dual-color-field phase difference is realized in a short distance, and the elliptically polarized terahertz (THz) radiation is easily obtained. By adjusting the back pressure of gas, THz radiation with ellipticity of 0.438 is generated. The simulated result based on the transient photocurrent model is consistent with that from the experiment, which reveals the mechanism of combined action of photocurrent and plasma dispersion.