Design And Research Of Terahertz To Infrared Radiation Converter

The wavelength of the electromagnetic wave lies in the range of 0.03-3mm,and between the infrared and millimeter waves, which is defined as terahertz. It has some unique properties: wide band, coherent characteristics, low energy characteristics, transient characteristics, spectral characteristics absorption characteristics, penetration characteristics, etc. Because of these characteristics, terahertz technology can be widely used in military, communication, biomedical, security inspection and other fields, and has been widely concerned and researched all the world. The metamaterials has the characteristics of negative permeability, negative dielectric constant and negative refractive index, and has great development prospects in the terahertz field. Combined with the infrared detection technology, this paper design a terahertz to infrared radiation converter, using a metamaterial absorber structure absorbs terahertz and convert the energy into infrared radiation, and then using infrared detector detects the signal.As the most important part of the converter, the metamaterial absorption structure needs to be efficient absorption of terahertz waves. We designed a metamaterial absorber structure, which consists of a split ring resonator(SRR), the dielectric layer and the metal reflection layer, and studied the absorption mechanism of metamaterial structure. then simulated the THz absorption properties by CST, as a result, the absorption rate is 99% at 0.5THz and 2.5THz. We also analyzed the absorption properties, including the surface current distribution, energy distribution and so on. And analyzed the influence of structure parameters on the THz response, by adjusting the structure size, the thickness of dielectric layer, the line width, the incident angle of THz etc, and then simulating.The metamaterial absorption structure which supported by flexible fim was prepared by lithography technology, magnetron sputtering and stripping process. The SRR array structure was complete and uniform, and the width of line is about 3.5μm, which is consistent with the pattern on the mask. We studied the experiment procedures and parameters, and analyzed the influence of the steps and the parameters on the quality of the lithography. Then tested and analyzed the THz response properties of the metamaterial absorption structure, and the results are consistent with the simulation results.In this paper, graphite is used as infrared emitter material, we studied the materials, the ratio of each material, the experiment procedures and the parameters of preparation of graphite. The graphite coating which we prepared was uniform and complete, we studied the relationship between the thickness of the graphite coating and the emittance by FTIR testing, the infrared absorption rates increases with the increase of thickness. And we analyzed the absorption rates and heat capacity of the converter, when the thickness of graphite is 8μm, the graphite layer has high infrared absorption rates at the wavelength of 10μm and converter has small heat capacity., and the absorption rates is about 80%.