Quantum generation by the interaction between clusters and the relativistic optical high field

通过研制利用超短峰值功率激光脉冲制造的强短脉冲辐射源，旨在了解相对论性光学高场（超强光子场）与星团之间的相互作用。首先，我们研制了产生相对论性光场所必需的10TW级激光系统。其次，将星团暴露在相对论光学高场中。这种相互作用产生了强MeV电子束、y射线、质子束。此外，还找到了有效产生这些高能辐射的方法。在本财政年度，我们将整个实验设备，包括10TW激光系统，从筑波大学转移到大阪大学，因为首席研究员已经转移。为了从团簇中产生强辐射，泵浦脉冲应短于20fs，且无预脉冲。然后将10TW系统的前置放大器由通常的再生式放大器改为光参量啁啾脉冲放大器。通过与脉冲切片器相结合，预脉冲与主脉冲的对比度优于10^<12>。此外，通过采用非共线性几何结构，可以实现宽带放大。在本研究中，我们将振荡器从20fs型改为lOfs型。然后，种子脉冲的带宽变为100nm。该种子脉冲被OPCPA与BBO放大。估计放大系数大于10^6，观察到的放大脉冲带宽为62nm。这个种子脉冲有足够的潜力被压缩到15fs。

Through the development of the strong short pulse radiation source which is made by using the ultrashort high peak power laser pulse, we aimed to understand the interaction between the relativistic optical high field (super strong photonic field) and clusters. First, we develop the 10TW class laser system, which is necessary to generate the relativistic optical field. Next, clusters are exposed in the relativistic optical high field. The strong MeV electron beam, y-ray, proton beam are generated from this interaction. Moreover, the method of the effective generation of these high energy radiations are found.In this fiscal year, we moved whole the experimental apparatus which includes the 10TW laser system, from University of Tsukuba to Osaka University, because the head investigator has been moved. In order to generate the strong radiations from the cluster, the pump pulse should be shorter than 20fs, and pre-pulse free. Then the pre-amplifier of 10TW system should be changed from usual regenerative amplifier to optical parametric chirped pulse amplifier. By combining to the pulse slicer, the contrast ratio between the prepulse and the main pulse are thought to be better than 10^<12>. Moreover, by taking the non-colinear geometry, the wide band amplification is possible. In this research, we changed the oscillator from 20fs type to lOfs type. Then the band width of seed pulse becomes 100nm. This seed pulse was amplified by OPCPA with BBO. The amplification factor was estimated to be over 10^6, the observed band width of the amplified pulse was 62nm. This seed pulse has enough potential to compressed to 15fs.