We first examined a temperature-dependent Sellmeier equation for the extraordinary refractive index of MgO-doped stoichiometric LiTaO3 (MgO:SLT) crystal via frequency-tunable narrowband terahertz (THz) generation at 0.4–1.8 THz and at a low temperature range of 80–300 K. The mean deviation of Sellmeier equation fit was less than 0.3%, being equivalent with the predicted measurement uncertainty of 0.3%. The temperature effect (dn THz/dT) was 2.02 × 10−3/K at 1 THz. Moreover, we showed the smaller birefringence for MgO:SLT than MgO-doped stoichiometric LiNbO3 at 300 K from THz time-domain spectroscopy. This study is crucial for material study itself and THz device engineering.

... In addition, we compared the refractive indices for SLT and stoichiometric LN (SLN) at a THz range 0.1–2 THz via a commercial THz-TDS system (TeraView TPS 3000) in the frequency range of 0.6–2 THz with a spectral resolution of 0.0075 THz (0.25 cm −1 ) at room ...
For more information about TeraView see http://www.azom.com/suppliers.aspx?SupplierID=12145
for full paper see http://iopscience.iop.org/article/10.7567/JJAP.56.040303/meta