多频多色光谱角色散束匀滑新方案

典型的光谱角色散技术中,由于光束带宽受限于高效三倍频,因而无法通过增大带宽来进一步改善焦斑均匀性.结合对四色打靶方案和多级相位调制技术的综合分析,提出了多频、多色光谱角色散束匀滑新方案.该方案能在保持高效三倍频基础上,获得带宽有所加宽,光谱包络近似连续的光源,且在远场匀滑上具有更为独特的优势.结果表明,采用束匀滑新方案后,虽然焦斑会有所增大,但其均匀性却得到明显改善;与典型的束匀滑方案相比,该方案能更为有效地抑制热斑,且达到最佳匀滑效果所需的时间有所减短.此外,通过对阵列光栅中子光栅刻线方向的自由组合可以实现多维光谱角色散的效果.

A novel scheme of beam smoothing using multi-central frequency and multi-color smoothing by spectral dispersion

In typical techniques of smoothing by spectral dispersion (SSD), illumination uniformity cannot be further improved by increasing the pulse bandwidth due to the limitation of high-efficiency frequency tripling. Combined with the analysis of the schemes of four-color beam smoothing and multi-frequency modulator SSD, a novel scheme of beam smoothing using multi-central frequency and multi-color smoothing by spectral dispersion has been proposed, which not only can achieve high-efficiency frequency tripling, but also can obtain laser beams with nearly continuous spectrum and exhibit some specific advantages in far-field smoothing. Results show that the focal spot will be enlarged slightly but obviously further smoothed by the use of the new scheme. Compared to the typical SSD technique, the new scheme can decrease hot spots effectively and achieve the best irradiation in less time. Moreover, with independent combination of dispersion directions in each quadrant of grating array, a multi-dimensional smoothing on focal spot can be realized.