进行了飞秒强激光与自由空气和充气毛细管相互作用产生三次谐波的实验研究,成功地获得了功率达0.17 GW、重复频率为10 Hz的紫外三次谐波信号.谐波的转换效率达到0.04%.对自由空气和充气毛细管中的谐波转换效率和谐波空间分布特性进行了比较.实验表明微毛细管虽然使谐波转换效率略有降低,但能有效地改善谐波的空间分布,使其更好地满足实际应用的需要.

Generation of the third harmonic from the interaction between femtosecond intense laser pulses and atmosphere air is studied. The UV third harmonic with power as high as 0.17 GW and 10HZ repetition is obtained successfully. An efficiency of third-harmonic generation is up to 0.04%. The conversion efficiency and mode structure of the harmonics generated in free air and microcapillary are compared. The experimental results show that the conversion efficiency of THG is a little lower in capillary, but its radial profile is improved effectively which will benefit to practical application.