从耦合波方程出发,分别在小信号、高功率密度(1.5 GW/cm2)条件下研究了晶体串接三次谐波(THG)转换方案,并利用实验验证了该方案。实验观察到这种方案可以有效提高宽带激光三次谐波转换效率,但混频晶体之间的距离对宽带三次谐波转换效率影响明显。在1.5 GW/cm2平均功率密度下,实验中最佳距离25 mm处,对带宽3.5 nm的啁啾脉冲取得了19.75%的三倍频效率,这对于高功率激光宽带三次谐波转换的解决很有意义。

The dual-tripler scheme for third harmonic generation (THG) is studied by the coupled equations under the small signal and high power condition (1.5 GW/cm2). The design has been proved in the experiment. It found that this design can increase the third harmonic conversion efficiency of broad bandwidth, but the distance between two triplers has an important impact on the third harmonic conversion efficiency in the experiment. 19.75% THG efficiency with chirp pulse of 3.5 nm bandwidth at average power of 1.5 GW/cm2 was achieved at 25 mm optimum distance between two triples in the experiment. It will be useful to solving the problem of the large bandwidth of the THG in the high power laser system.