A front end system with spatiotemporal smoothing based on the use of multimode optical fibre has been developed on the Luch laser. The system consists of a broadband master oscillator, a smoothing fibre, preamplifiers, and subsystems for the formation of temporal and spatial radiation profile. The processes of generation of partially coherent radiation, its amplification and conversion into the second harmonic are experimentally investigated. At the amplifying channel output, the pulse energy of the first harmonic reaches up to 1200 J with a pulse duration of 4 ns; the technical coefficient of radiation conversion to the second harmonic is up to 44%, and the beam divergence is 0.2 – 0.25 mrad. When using smoothed radiation, the speckled structure in the far field is almost completely eliminated: the small-scale inhomogeneity of the target irradiation, integrated over the pulse time, is reduced by 1 – 2 orders of magnitude compared to unsmoothed radiation.

在 Luch 激光器上开发了基于使用多模光纤的具有时空平滑的前端系统。该系统由宽带主振荡器、平滑光纤、前置放大器和用于形成时间和空间辐射剖面的子系统组成。实验研究了部分相干辐射的产生、放大和转换成二次谐波的过程。在放大通道输出端，一次谐波的脉冲能量高达1200 J，脉冲持续时间为4 ns；辐射转换成二次谐波的技术系数高达44%，光束发散度为0.2 – 0.25 mrad。使用平滑辐射时，远场中的斑点结构几乎完全消除：