Opt Lett. 2023 Apr 1;48(7):1930-1933. doi: 10.1364/OL.485007.
We present spatially enhanced electric-field-induced second-harmonic (SEEFISH) generation with a chirped femtosecond beam for measurements of electric field in mesoscale confined geometries subject to destructive spurious second-harmonic generation (SHG). Spurious SHG is shown to interfere with the measured E-FISH signal coherently, and thus simple background subtraction is not sufficient for single-beam E-FISH approaches, especially in a confined system with a large surface-to-volume ratio. The results show that a chirped femtosecond beam is effective in preventing higher-order mixing and white light generation in windows near the beam focal point which further contaminates the SEEFISH signal. The successful measurements of electric field of a nanosecond dielectric barrier discharge in a test cell demonstrated that spurious SHG detected with a congruent traditional E-FISH approach can be eliminated using the SEEFISH approach.
我们提出了一种具有啁啾飞秒光束的空间增强电场感应二次谐波（SEEFISH）产生方法，用于测量在受到破坏性杂散二次谐波产生（SHG）的介观受限几何形状中的电场。杂散 SHG 被证明会与测量的 E-FISH 信号相干干扰，因此对于单光束 E-FISH 方法，简单的背景扣除是不够的，特别是在具有大表面积与体积比的受限系统中。结果表明，啁啾飞秒光束可有效防止在光束焦点附近的窗口中产生高阶混合和白光，这进一步污染了 SEEFISH 信号。在测试单元中对纳秒介电阻挡放电的电场的成功测量表明，使用 SEEFISH 方法可以消除用传统的 E-FISH 方法检测到的杂散 SHG。
