给出了ZnTe电光晶体折射率和吸收系数随太赫兹波频率而变化的计算曲线, 比较了太赫兹波在ZnTe中传播时的相速度和群速度。通过与太赫兹频率和晶体厚度相关的电光效率响应函数, 理论计算了ZnTe电光晶体对太赫兹脉冲的探测电光响应, 得到了晶体厚度与探测到的太赫兹频谱宽度的定性关系, 从计算结果中找到了ZnTe电光晶体在5.3 THz和6.2 THz等多个频点的探测盲点, 这些探测盲点来自于ZnTe电光晶体与相应频点太赫兹波的栅格共振吸收。结合自制的大口径太赫兹光导天线和1 kHz脉冲重复频率的太赫兹时域光谱实验系统, 通过差分探测技术, 从实验上得到了太赫兹波极化方向与〈110〉型ZnTe晶体晶轴方向的六个最佳匹配角度, 给出了太赫兹电场最大值随晶轴与太赫兹波极化方向之间夹角变化的曲线及经验公式, 这将有利于在实践中对该现象的深入理解和对探测灵敏度的有效提高。

The calculation curves of the refractive index and absorption coefficient of ZnTe electro-optic crystal with the frequency of terahertz wave were given, and the phase velocity and group velocity of terahertz wave propagating in ZnTe were compared. Through the electro-optic efficiency response function related to terahertz frequency and crystal thickness, the detection spectrum response of ZnTe electro-optic crystal to terahertz pulse was calculated theoretically and the relation between terahertz spectrum response bandwidth and crystal thickness was gotten qualitatively. From the calculation result, some detection blind spots were found such as 5.3 THz and 6.2 THz which come from the lattice resonances of ZnTe crystal with corresponding frequency terahertz wave. With a large aperture terahertz photoconductive antenna and a 1 kHz pulse repetition frequency terahertz time-domain spectroscopy experiment system, six optimum matching angles between the polarization direction of terahertz pulse and the crystal axis direction of <110> type ZnTe crystal were obtained experimentally by differential detection technology. The curve and empirical formula of the change of the maximum terahertz electric field with the angle between the crystal axis and terahertz wave polarization direction were given, which will be beneficial to in-depth understanding of the phenomenon and the effective improvement of detection sensitivity in practice.