(100)MgO和(100)LaAlO_3高温超导基片材料THz时域光谱研究

Time-domain terahertz spectroscopy of (100)MgO and (100)LaAlO_3 substrates

THz波段位于微波与红外之间 ,该波段电磁波与物质的相互作用是一个崭新的研究领域 .应用THz时域光谱技术研究了两种重要的单晶基片材料 (1 0 0 )MgO和 (1 0 0 )LaAlO3的THz光谱 .在 0 2— 2THz频率范围 ,得到这两种材料在THz波段的光学参数 .结果表明 ,在THz波段MgO基片材料的折射率 n和介电系数 ε不随频率的变化而变化 ,而LaAlO3基片材料的折射率和介电系数随着频率的增加而略有增加 .在 1THz频率处 ,测得MgO的复折射率 n =3 4 6+i0 0 0 1 ,复介电系数 ε =1 2 2 7+i0 0 6 ;LaAlO3的复折射率 n =4 78+i0 0 2 ,复介电系数 ε =2 2 5 +i0 2 在THz波段 ,LaAlO3基片的介电损耗tanδ约为MgO的 5倍 ,且两者的介电损耗值均小于 0 0 1 。

THz(teraherz)properties of high_ T c superconductor substrates(100)MgO and (100)LaAlO 3 are measured using time_domain spectroscopy at frequency range between 0 2 and 2 THz.The complex refractive index and dielectric function of the MgO substrate is independent of frequencies;those of LaAlO 3 increase slightly with increasing frequency.We determine =3 46+i0 001 and =12 27+i0 06 for the MgO substrate and =4 78+i0 02 and =22 5+i0 2 for the LaAlO 3 substrate at 1THz.The dielectric loss tan δ of both LaAlO 3 and MgO substrate is less than 0 01 The tan δ of LaAlO 3 in nearly five times larger than MgO,but both of them are less than 0.01.