窄脉宽高重频激光放大器实验研究

报道了采用一种紧凑型、低成本和角度复用的板条 多通放大器,并对窄脉宽高重复频率种子激光进行多通放大的实验研究。通过使用角度复用 多通结构,可以有效 使用增益介质,光在介质内不走重复路径,相对于走重复路径的偏振复用结构,可减少进入 主振荡器的反 馈,抑制寄生振荡。实验过程中,分别采用直通和内全反射两种入射方式对种子光进行放大 。注入脉宽 为2.5ns、重复频率20kHz、平均功率为0.5W的Nd:YAG/Cr⁴⁺:YAG被动调Q种子 光,采用内全反射方式进 行三通放大时,得到了3.2W的最大平均功率输出,表明内全反射方 式比直通型方式能更有效地实现光放大、减小热畸变、改善光束质量和提高输出功率。

Experiment study of narrow pulse width and high repetition frequency laser amplifier

A compact,lower cost,angular multiplexing multi-pass slab amplifier is reported.The traditional rod structure has serious optical distortion,including thermal focusing,doub le focusing caused by stress,stress birefringence.The slab structure can reduce the impact of these effects,and impr ove the quality of laser beam.The slab laser geometry permits efficient use of the unsaturated gain mediu m by using angular multiplexing.Standard methods,such as polarization multiplexi ng,require the beam to be near to retrace its path.This retracing can result in feedback into the oscillator source and will,lead to par asitic oscillation of the amplifier.These problems due to retracing its path can be reduced if using angul ar multiplexing.A passively Q switched laser with repetition frequency of 20kHz,pulse duration of 2.5ns and average output power of 0.5W is used as the master oscillator.Comparing the two ways of three-pass amplificatio ns,we realize a method to effectively amplify the seed laser with nanosecond pulse duration and microjoule energy.Whe n the seed laser is totally reflected in the Nd:YVO_4slab,the average output power of 3.2W is achieved.Compared wit h other methods,this method can obviously eliminate the thermal lensing effect and enhance the output power.