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利用太赫兹时域光谱系统,在0.5～9.5 THz范围内对氧化镁单晶基片的介电特性进行了研究,并获得折射率、吸收系数以及复介电函数信息.实验数据表明,在低频(＜2 THz)范围内,氧化镁单晶透过性较好,折射率在3.12～3.15之间.折射率和吸收系数均随频率增加而增大,且在3.16 THz和8.11 THz两处存在明显的吸收峰.通过经典的赝简谐振动理论很好地拟合了实验结果,分析了晶体中的横向光学声子振动模式,为氧化镁单晶在宽带太赫兹波段的应用提供了有益参考.“,”The dielectric properties of single-crystal MgO were studied by terahertz time-domain spectroscopy in the frequency range extending from 0.5 to 9.5 THz.The refractive index,power absorption,and the complex dielectric function were extracted from experimental data.At low terahertz frequencies band (＜2 THz),the absorption coefficient was extremely low and increased with increasing frequency.Meanwhile the corresponding refractive index had low dispersion,increasing from 3.12 to 3.15.Two prominent resonances were observed at 3.16 THz and 8.11 THz and were well-described by a multiple-oscillator model through theoretical fitting.The interaction of incident photons and the transverse optical (TO) phonons in the crystal were studied and it gives good evidence to further applications in developing broadband terahertz components and terahertz spectroscopy.