图  1  激光场中的QED级联示意图，箭头向右表示电子，箭头向左表示正电子，波浪线表示高能光子

Figure  1.  Schematic diagram of a QED cascade in a super-strong laser field, double solid lines directed rightwards/leftwards represent electrons/positrons, and wavy lines represent high-energy photons

图  2  在两束线偏振激光对向碰撞情况下，参数${\chi _{{\rm{e}},{\text{γ}} }}$的最大值与激光强度（$\lambda = 1{\text{ μm}}$）的变化关系

Figure  2.  Maximum value of parameter ${\chi _{{\rm{e}},{\text{γ}} }}$ as a function of laser intensity ($\lambda = 1{\text{ μm}}$) in the case of counter-propagating linearly polarized lasers

图  3  在两束线偏振激光对向碰撞情况下，伽马光子发射和正负电子对产生的概率与激光强度的变化关系

Figure  3.  Photon emission probability and positron-electron pair creation probability as a function of laser intensity ($\lambda = 1{\text{ μm}}$) in the case of counter-propagating linearly polarized lasers

图  4  两束对向传播激光与薄固体靶相互作用下，在y=0处的正电子密度时空演化图[(a)和(c)]以及高能光子密度的时空演化图[(b)和(d)]，其中图[(a)和(b)]和[(c)和(d)]分别显示了激光强度为4×10²³和1.2×10²⁴ W/cm²的情况^[36]

Figure  4.  Spatiotemporal evolutions of the positron (a) and (c) and high-energy photon (b) and (d) densities at y = 0 in the case of counter-propagating linearly polarized lasers interaction with solid targets, where sub figures (a) and (b) and (c) and (d) are shown for the cases with the laser intensities of 4×10²³ and 1.2×10²⁴ W/cm², respectively ^[36]