Polarization-Sensitive Electro-Optic Sampling of Elliptically-Polarized Terahertz Pulses: Theoretical Description and Experimental Demonstration
Polarization-Sensitive Electro-Optic Sampling of Elliptically-Polarized Terahertz Pulses: Theoretical Description and Experimental Demonstration
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DOI：
10.3390/particles2010006
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发表时间：
2019-01
期刊：
影响因子：
1.4
通讯作者：
K. Oguchi;M. Okano;S. Watanabe
中科院分区：
文献类型：
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作者：
K. Oguchi;M. Okano;S. Watanabe
我们回顾了我们最近的工作偏振敏感电光（PS-EO）采样，这是一种方法，使我们能够测量椭圆偏振太赫兹时域波形，而不使用线栅偏振器。由于所采用的探测脉冲和待分析的椭圆偏振太赫兹脉冲之间的相位失配，探测脉冲在EO晶体内传播期间感测不同的太赫兹电场（E场）矢量。为了解释电光晶体内部的复杂情况，我们用“频域描述”来表示预期的电光信号，而不是依赖于传统的普克尔斯效应描述。利用这种方法，我们得到了两个重要的结论：（1）由于两个相互正交方向的电场的相对幅度和相位不受相位失配的影响，因此可以精确地测量每个频率分量的偏振态，而与电光晶体的选择无关;以及，（ii）椭圆极化电场矢量的时域波形可以通过考虑相位失配、吸收和探测脉冲宽度的影响来恢复。我们通过使用不同的EO晶体进行检测，实验证实了上述两个结论。这澄清了我们的理论分析的有效性的基础上的频域描述和有用的PS-EO采样。
We review our recent works on polarization-sensitive electro-optic (PS-EO) sampling, which is a method that allows us to measure elliptically-polarized terahertz time-domain waveforms without using wire-grid polarizers. Because of the phase mismatch between the employed probe pulse and the elliptically-polarized terahertz pulse that is to be analyzed, the probe pulse senses different terahertz electric-field (E-field) vectors during the propagation inside the EO crystal. To interpret the complex condition inside the EO crystal, we expressed the expected EO signal by “frequency-domain description” instead of relying on the conventional Pockels effect description. Using this approach, we derived two important conclusions: (i) the polarization state of each frequency component can be accurately measured, irrespective of the choice of the EO crystal because the relative amplitude and phase of the E-field of two mutually orthogonal directions are not affected by the phase mismatch; and, (ii) the time-domain waveform of the elliptically-polarized E-field vector can be retrieved by considering the phase mismatch, absorption, and the effect of the probe pulse width. We experimentally confirm the above two conclusions by using different EO crystals that are used for detection. This clarifies the validity of our theoretical analysis based on the frequency-domain description and the usefulness of PS-EO sampling.