采用固相反应法制备了高品质0.3BaSrTiO3-0.7NdAlO3微波介质陶瓷,并采用太赫兹时域光谱对该陶瓷在太赫兹波段内的吸收特性进行研究。结果显示,在18 ℃(291 K)下该陶瓷的吸收系数可由外部光泵进行调制,在0.55 THz时调制度可达到34.46%。通过拟合0.45 THz和0.55 THz处0.3BaSrTiO3-0.7NdAlO3陶瓷的介电常数与光功率之间的关系,可以得到这两个频率处的非简谐系数α分别为1.273×10 -8和1.823×10 -8。此外,吸收系数随外部光泵强度调制的微观机理是由激发的自由载流子引起0.3BaSrTiO3-0.7NdAlO3陶瓷的内部空间电荷场所致。

In this study, high quality 0.3BaSrTiO₃-0.7NdAlO₃ microwave dielectric ceramics are prepared using solid state reaction method. Their absorption characteristics in the terahertz range are investigated using terahertz time-domain spectroscopy. It is observed that the absorption coefficient could be modulated using the external optical pump at the 18 ℃(291 K), and the tunability could reach up to 34.46% at 0.55 THz. By fitting the dielectric constant and light power of 0.3BaSrTiO₃-0.7NdAlO₃ ceramics at 0.45 THz and 0.55 THz, the anharmonic parameter α are observed to be 1.273×10 ^-8 and 1.823×10 ^-8, respectively. In addition, the micro-mechanism of absorption coefficient modulation with the intensity of external light pump is attributed to the internal space charge field in the 0.3BaSrTiO₃-0.7NdAlO₃ ceramics caused by the excited free carriers.