Research Of Terahertz Modulation Characteristics Based On CTNA Ceramics

Terahertz modulation technology is one of the important part in the area of terahertz research.The modulator based on composite ceramics has been widely used in the field of microwave,but there is less research in the area of terahertz research.In this article we studied the photoelectric properties of xCaTiO₃-?1-x?NdAlO₃ composite ceramics?CTNA?,we also proposed a new kind of metamaterial absorber?MA?based on this kind of ceramic.The CTNA ceramics were prepared via solid-state reaction method,the complex dielectric constants of the CTNA ceramics were measured by employing a terahertz time-domain spectroscopy system.As for the MA,we carried out a simulation experiment by using CST a kind of software based on finite integral in time domain.The main content of my work are as follows:?1?The 532nm optical pump is used to study the terahertz modulation characteristics of0.45CaTiO₃-0.55NdAlO₃ composite ceramics.When the light intensity is 350mW the modulation depth of the real part of the dielectric constant of the sample reaches 10.5%.And the change of the refractive index of the sample is proportional to the intensity of the external light.Further theoretical analysis pointed out that the modulation properties were caused by the redistribution of the electrons influenced by the external optical field.We also found that the dielectric constant of xCaTiO₃-?1-x?NdAlO₃ composite ceramics will increase with the increase of x,and the tunability will improve too.?2?Bsaed on the complex dielectric constant of 0.45CaTiO₃-0.55NdAlO₃ ceramics obtained by former experiment we designed a kind of terahertz MA.The absorption peak of the absorber reached 98%at 0.73THz and the absorption of the electromagnetic energy due to Mie resonance.We also studied the influence of structural parameters on the absorber.We found that the absorption peak moves to the high frequency direction when the height of the absorber unit is decreased which is coincident with the Mie Resonance theory.We also found that the distance of the periodic unit also affects the absorption peak.By simulating the influence of the external light field we found that the absorption peak moves to the low frequency direction when increasing the intensity of the external optical field which means the absorber can be tuned by applying an external optical field.