Investigation of Optical Tuning on the Dielectric Properties of 0.3Ba0.4Sr0.6TiO3–0.7NdAlO3 Ceramics in Terahertz Range

Abstract

Optical tuning of the dielectric properties of 0.3Ba 0.4 Sr 0.6 TiO 3 -0.7NdAlO 3 ceramics under external optical fields was investigated in a frequency range from 0.2 to 0.8 THz at room temperature. It could be found that the dielectric constant could be modulated by an external optical pump and the tunability of permittivity reached up to 18% at 0.7 THz. Results showed that the real part of permittivity increased upon application of an external optical field, which could be interpreted as hardening of the soft mode and increasing of the damping coefficient and oscillator strength. The experimental results also showed that the change of the refractive index has a linear relationship on the scale with the applied external light power. And these results were attributed to the built-in electric field caused by the excited free carriers in the ceramics. The results of the present experiment provide a reference for further development of tunable structures controlled by an external optical field. Our results should be a reference for future research of the tunable terahertz devices modulated by external optical field, such as terahertz modulator.