Time-domain terahertz spectroscopy of (100) (LaAlO3)(0.3)-(Sr2AlTaO6)(0.7)substrate

We measured terahertz (THz) properties of high-T-c superconductors (HTS's) substrates. (100) MgO and (100) (LaAlO3)(0.3)-(Sr2AlTaO6)(0.7) (LSAT), at f requencies between 0.5 THz and 2 THz using time-domain terahertz spectrosco py (TDTS). The complex refractive index ti and dielectric function <(<is an element of>)over bar> of the MgO substrate were independent of frequencies , those of LSAT slightly increased with increasing frequency. It was determ ined that (n) over tilde = 3.17 + i0.004 and <(<is an element of>)over bar> = 10.1 + i0.06 for the MgO substrate and (n) over bar = 4.8 + i0.02 and <( <is an element of>)over tilde> = 24 + i0.2 for the LSAT substrate at 1 THz. The LSAT values were almost independent of the temperature at these freque ncies. The dielectric loss tan delta 's of the LSAT and the MgO substrates were less than 0.01. The tan delta 's of LSAT were several times larger tha n those of MgO, and increased with an increase of frequency.