Fig. 1. Sketch of QED cascade triggered by ultra-intense laser and the depletion of the field

Fig. 2. Distributions of y component of electric field, and density of γ photons and electron positron pairs

Fig. 3. Normalized peak intensity evolution from analytical calculation based on Eq. (8) and PIC simulations, where the cases 1～4 represent the parameters of Fig.2(a)～Fig. 2(d), respectively 基于式（8）和PIC模拟得到的归一化强度 在不同情形下的演化结果，其中情形1～4分别对应于图2(a)～图2(d)的四种情况

Fig. 4. Attainable peak intensity I₁ as a function of vacuum electron residual density for linearly and circularly polarized pulse with τ₀=5λ/c, ω₀=3λ, waist of laser for linearly polarized pulse with τ₀=5λ/c and duration of the laser for linearly polarized pulse with ω₀=3λ

Fig. 5. Ratio between real attainable peak intensity I₁ and design peak intensity I₀ as a function of vacuum electron residual density for (a) linearly and (b) circularly polarized case with τ₀=5λ/c, ω₀=3λ

Fig. 6. Attainable peak intensity for different vacuum electron residual density as a function of beam waist and beam duration