Temperature dependent refractive index and dielectric modulation of paramagnetic magneto-optic PrF3 crystal with terahertz time-domain spectroscopy

PrF₃ crystals are excellent paramagnetic magneto-optical materials. In this paper we report on the PrF₃ complex refractive index and the complex permittivity in terahertz (THz) frequency range. Measurements have been performed using transmission time domain terahertz spectroscopy (THz-TDS). The influence of temperature on the complex refractive index and the complex permittivity was also investigated. To the best of authors knowledge this dependency have not been reported thus far. We show that complex refractive index increases with temperature (50 K–170 K), so do the values of complex permittivity and loss tangent. A relatively small (~0.02) increase of loss tangent value is obtained for all frequencies (0.4THz-1.4 THz) at 170 K contrary to 50 K. It's worth mentioning the permittivity of PrF₃ exhibits better thermal stability than CeF₃ between 0.75 THz and 0.9 THz. Our research shows PrF₃ is an excellent candidate for optoelectronic tunable application in THz frequency, especially between 0.75 THz and 0.9 THz when the temperature varies dramatically.