Fig. 1. Experimental setup.实验布局图

Fig. 2. Peak E-field magnitude versus laser intensity in the four different directions. 不同激光强度下, 四个方向上对应的电场峰幅值

Fig. 3. Electric field waveforms detected by the monopole antenna-3 at laser intensities of (a) 5.7 × 10¹⁴, (b) 7.4 × 10¹⁴, (c) 1.5 × 10¹⁵, (d) 2.0 × 10¹⁵, (e) 2.9 × 10¹⁵, and (f) 6.2 × 10¹⁵ W/cm². 入射激光强度分别为(a) 5.7 × 10¹⁴, (b) 7.4 × 10¹⁴, (c) 1.5 × 10¹⁵, (d) 2.0 × 10¹⁵, (e) 2.9 × 10¹⁵, (f) 6.2 × 10¹⁵ W/cm²时, 靶前靠近法线方向上的电场时间波形

Fig. 4. Frequency spectra of the electric fields detected by the monopole antenna-3 at laser intensities of (a) 5.7 × 10¹⁴, (b) 7.4 × 10¹⁴, (c) 1.5 × 10¹⁵, (d) 2.0 × 10¹⁵, (e) 2.9 × 10¹⁵, and (f) 6.2 × 10¹⁵ W/cm². 入射激光强度分别为(a) 5.7 × 10¹⁴, (b) 7.4 × 10¹⁴, (c) 1.5 × 10¹⁵, (d) 2.0 × 10¹⁵, (e) 2.9 × 10¹⁵, (f) 6.2 × 10¹⁵ W/cm²时, 靶前靠近法线方向上电场的频谱分布

Fig. 5. Electric field waveforms and their corresponding frequency spectra detected by the four monopole antennas. (a) and (e) correspond to the monopole antenna-1, (b) and (f) correspond to the monopole antenna-2, (c) and (g) correspond to the monopole antenna-3, (d) and (h) correspond to the monopole antenna-4. The laser intensity is 1.5 × 10¹⁵ W/cm². 入射激光强度为1.5 × 10¹⁵ W/cm²时, 不同方向测量的电场波形及其频谱分布　(a)和(e)对应单极天线-1; (b)和(f)对应单极天线-2; (c)和(g)对应单极天线-3; (d)和(h)对应单极天线-4

Fig. 6. Electric field waveforms and their corresponding frequency spectra detected by the four monopole antennas. (a) and (e) correspond to the monopole antenna-1, (b) and (f) correspond to the monopole antenna-2, (c) and (g) correspond to the monopole antenna-3, (d) and (h) correspond to the monopole antenna-4. The laser intensity is 6.2 × 10¹⁵ W/cm². 入射激光强度为6.2 × 10¹⁵ W/cm²时, 不同方向测量的电场波形及其频谱分布　(a)和(e)对应单极天线-1; (b)和(f)对应单极天线-2; (c)和(g)对应单极天线-3; (d)和(h)对应单极天线-4

Fig. 7. Radiation energy versus laser intensity at different directions: (a) Total radiation energy detected by the antennas; (b) radiation energy at frequencies lower than 0.3 GHz; (c) radiation energy at frequencies upper than 0.3 GHz.不同方向测量的微波辐射能量随激光强度的变化(a)单位立体角内产生的总辐射能; (b)单位立体角内产生的0.3 GHz以下的辐射能; (c)单位立体角内产生的0.3 GHz以上的辐射能