对高强度超短脉冲单块BBO晶体产生三倍频的过程进行了理论及实验研究。定量分析入射基频光强度、晶体厚度、晶体失谐角和方位角等因素对三倍频光转换效率和时间波形的影响,并对实验参数进行了优化。针对脉冲宽度100fs、带宽25nm、中心波长810nm、能量为6mJ左右的超短脉冲基频光,采用单块BBO晶体开展了三倍频实验研究,获得了0.8%的三倍频转换效率,并对实验结果进行了分析。在此基础上,进一步提出了提高单块BBO晶体超短脉冲三倍频转换效率的改进措施。

The third harmonic generation of the super intense ultrashort pulse with a single β-barium borate (BBO) crystal was studied theoretically and experimentally.The effects of the intensity of the fundamental field,the thickness,the detuned angle and the azimuth angle of the crystal on the conversion efficiency and the pulse shape were analyzed.The parameters of the experiment were optimized.The corresponding experiment was performed for the ultrashort pulse with center wavelength of 810 nm,the pulse width (FWHM) of 100 fs,the bandwidth of 25 nm and the pulse energy of about 6 mJ by using a single BBO crystal.The conversion efficiency of the third harmonic generation can approach 0.8%.Analyzing the experimental results,we proposed the methods for improving the conversion efficiency of the third harmonic generation with a single BBO crystal.