为解决已有太赫兹(THz)表征系统对样品性质表征不够全面的问题,搭建了基于硒化镓(GaSe)晶体的宽谱THz系统,利用飞秒脉冲激光泵浦GaSe晶体,产生频谱范围为10~20 THz的宽谱THz波。搭建了迈克耳孙干涉仪对THz瞬态电场进行非相干表征,用该系统测量了尿嘧啶等三种生物样品的高频吸收谱,并通过密度泛函理论对生物分子的振动、转动情况进行了理论分析。测量结果与理论结果相吻合,证明了该系统可快速获取样品的高频信息,弥补了传统THz光谱系统在高频波段的信息缺失,为搭建高频THz时域光谱系统打下坚实的基础。

In order to solve the problem that the existing terahertz (THz) characterization system does not fully characterize the sample properties, a wide-spectrum THz system based on gallium selenide (GaSe) crystals is built. Femtosecond pulse laser is used to pump the GaSe crystals, and the generated THz radiation has a broad spectral range of 10 to 20 THz. A Michelson interferometer is built to perform non-coherent characterization of the THz transient electric field. The high-frequency absorption spectra of three kinds of biological samples such as uracil are measured by the system, and the vibration and rotation of biomolecules are analyzed theoretically with density functional theory. Experimental results are in agreement with the theoretical calculations, proving that the system can quickly obtain the high-frequency information of the sample. The system makes up for the lack of information in the high-frequency band of the traditional THz spectral system and lays a solid foundation for building a high-frequency THz time-domain spectral system.