中文摘要：

利用光泵浦-太赫兹（THz）探测（OPTP）技术,研究了THz波在Si半导体界面间的传输行为。通过改变抽运光密度从而改变样品表面的载流子浓度,实现对THz波透射/反射的有效调制。在外加中心波长为800nm的飞秒激光激发块体半导体Si片时,成功实现了对宽带THz波时域谱包括入射THz脉冲振幅和相位以及THz波次级反射峰抗反射的调制。光激发Si片可以获得任意载流子浓度的Si片实现对THz脉冲振幅的调制,调制度达到90%以上;光激发Si片能够使THz脉冲的相位发生负延迟,随着泵浦光密度的增加,负的相移越来越明显,随着频率的增高,负的相移也越来越明显;光激发Si片还能够对THz波的次级反射峰进行调制,随着泵浦光密度的改变,实现对次级反射峰的π相位以及次级反射峰抗反射的调制。光激发Si片对宽带THz波时域谱的调制为THz波在通信、国防安全等领域的应用奠定了基础。

英文摘要：

Using optical pump-terahertz（THz）probe（OPTP）technology and changing the carrier concentration of the sample,we achieve the effective modulation of the THz transimition/reflection when changing the pump fluence.With the pump beam at 800 nm,we achieve the effective modulation on THz time domain spectroscopy.The modulation of THz time domain spectroscopy includes the modulation of the ampiltude and phase of THz wave,and the modulation of secondary reflection peak of THz wave by changing the pump fluence.With varying the pump fluence,more than 90% modulation of the ampiltude of THz wave can be achieved.Another phenomenon we observed is that a negative time shift of the terahertz pulse occurs when the silicon surface is photoexcited.With pump fluence increases,and the frequency increases,negative phase shift is becoming more and more obvious.Varing the pump fluence,the secondary reflection peak shows aπphase shift or zero phase shift relative to that of incident pulse,and it acts as a broadband terahertz pulse antireflection coating with proper pump fluence.This modulation of THz time domain spectroscopy can lay the foundation for the application of THz wave in communication,national defense and security fields.