紫外波长光成丝在大气中传输时的激光脉冲宽度研究

Laser Pulse Duration of the Ultraviolet Light Filament in Air

文章用数值模拟方法研究了脉冲宽度对紫外激光丝在大气中传输的影响.248 nm波长的紫外激光在空气中能够形成光丝的脉冲宽度达到4 ns,比红外波长激光的脉冲宽度高3个数量级.在大气中可以利用长达几个纳秒的紫外脉冲激光在1 TW/cm2的功率下实现长距离的激光丝传输.在适当的长脉冲宽度情况下,可以用不含时间的稳态麦克斯韦波动方程来研究激光丝传输,研究了脉冲宽度的范围.模拟计算选取3种波长,比较了激光丝在氮气中传输的情况,说明了这些激光脉宽依赖于光束的功率.

In this paper we present for the first time the detailed numerical simulation of the effects of laser pulse duration on uhraviolet light filament at various wavelengths. The upper limit of the pulse duration for the uhraviolet light at 248 nm to form the filament is up to 4 ns in air, which is about 3 orders of magnitude higher than that for the infrared light. The long-distanee filament propagation can be realized at the beam intensity of TW/cm^2 by using the ultraviolet pulse up to a few nanoseconds. The laser pulse duration has been studied in details in this paper by applying the steadstate Maxwell equation. Besides, the light filament propagation in nitrogen is compared. The simulation resuhs also show that the laser pulse duration is dependent on the particular heam intensity.