空气中等离子光栅诱导探测光丝三次谐波辐射放大的实验研究

对探测光丝的不同位置与等离子光栅相互作用和探测光丝作用到等离子光栅不同位置引起三次谐波的增强进行了实验研究.研究发现,探测光丝的三次谐波信号强度对于探测光丝不同位置与等离子光栅相互作用和等离子光栅内部钳制的激光强度具有极强的依赖关系.与等离子光栅相互作用,三次谐波信号与等离子光栅基波信号的相位匹配与否是解释探测光丝三次谐波信号强度变化的关键.控制探测光丝以小角度与等离子光栅相互作用是实现探测光丝三次谐波信号有效放大的最佳途径.

Efficient generation of third harmonic radiation of air filament induced by plasma grating

In this paper, the dependences of the third harmonic generation (THG) of a probe filament on the relative position of the probe filament interacting with the plasma grating and the position of the plasma grating interacting with the probe filament are investigated. The phase matching between the third harmonic of the probe filament and the fundamental wave of the plasma grating is earlier to achieve when the head of the probe filament interacts with the plasma grating, inducing the enhancement of the third harmonic generation, while the phase mismatching happens when the trail of the probe filament interacts with the plasma grating. The distribution of the clamping laser intensity inside the plasma grating results in the dependence of the THG on the positions of the plasma grating interacting with the probe filaments. It is an effective method of promoting the THG by setting the crossing angle between the probe filament and the plasma grating to be very small.
Keywords：plasma gratingthird harmonic generationcoherent subtraction