In recent decades, with the rapid development of terahertz generator and detector, more and more people are focus on the research of propagation of terahertz wave, one of which is terahertz modulator. Ferroelectric materials play an important role in the research of functional devices operating in the THz range because of their response time, dielectric loss and tunability.

With the guidance of Professor Jianquan Yao, Jie Ji et. al in the Wuhan National Laboratory for Optoelectronics investigated the dielectric spectra of multilayer PZT/PT superlattice thin films under an external optical field at room temperature by time-domain terahertz spectroscopy. In addition, they compared the dielectric spectra of single layer PT and PZT thin film with the PZT/PT superlattice thin film. Results showed that among the dielectric property of the three thin films studied, the tunability of the PZT/PT superlattice was the largest.

In June 28, 2016, the article ’’ Investigation of optical pump on dielectric tunability in PZT/PT thin film by THz spectroscopy ’’ was published in Optics Express under the OSA. This work was supported by the National Basic Research Program (973 Program) (Grant No.2015CB755403), the CAEP THz Science and Technology Foundation (No. AEPTHZ201402) and the CAEP THz Science and Technology Foundation (No. AEPTHZ201407). 

Fig.1. Time-domain signal waveforms of the substrate and air at room temperature. (b), (c), (d) are the time-domain signal waveforms of the single-layer PT, single-layer PZT, and multilayer PZT/PT thin films.

Fig.2 Measured dielectric spectra of thin films with different optical powers at room temperature.

 

Fig.3 Tunability of the ferroelectric thin films under different optical field powers at (a) 0.4 THz, (b) 0.5THz, (c) 0.6THz and (d) 0.8THz.