Terahertz optical properties and birefringence in single crystal vanadium doped (100) β-Ga 2 O 3

We report the terahertz optical properties of vanadium doped (100) β-Ga 2 O 3 using terahertz time-domain spectroscopy (THz-TDS). The V-doped β-Ga 2 O 3 crystal shows strong birefringence in the 0.2-2.4 THz range. Further, phase retardation by the V-doped β-Ga 2 O 3 has been measured over the whole THz range by terahertz time-domain polarimetry (THz-TDP). It is observed that the V-doped β-Ga 2 O 3 crystal behaves both as a quarter waveplate (QWP) at 0.38, 1.08, 1.71, 2.28 THz, and a half waveplate (HWP) at 0.74 and 1.94 THz, respectively.