We investigated the performance of electric-field-induced second-harmonic generation (E-FISHG) by spectroscopic measurement using high-intensity femtosecond laser pulses. The second-harmonic intensity increased quadratically versus the applied electric field, as expected from the theory, up to 15 kV/cm with the laser energy up to 2.5 mJ, which is ${\sim}{5}$ times higher than the observable optical breakdown threshold. In addition, when the laser energy was 2.8 mJ, ${\sim}{80}$ times signal intensity at 0.23 mJ was obtained. These results suggest that the electric-field measurement by E-FISHG with high-intensity second harmonics is expected by using high-intensity laser pulses above the observable optical breakdown threshold. Spectroscopic measurement shows no E-FISHG of white light generated by self-phase modulation in laser-induced filament.

中文翻译：

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在可见光击穿阈值之上使用高强度飞秒激光脉冲产生电场引起的二次谐波

我们通过使用高强度飞秒激光脉冲的光谱测量研究了电场诱发的二次谐波产生（E-FISHG）的性能。正如理论所预期的，二次谐波强度相对于外加电场呈二次方增加，高达15 kV / cm，激光能量高达2.5 mJ，比可观察到的高$ {\ sim} {5} $倍。光学击穿阈值。此外，当激光能量为2.8 mJ时，$ {\ sim} {80} $得到的信号强度为0.23mJ。这些结果表明，通过使用高于可观察到的光击穿阈值的高强度激光脉冲，可以预期通过具有高强度二次谐波的E-FISHG进行电场测量。光谱测量显示在激光诱导的灯丝中没有通过自相位调制产生的白光的E-FISHG。