Research On Terahertz Absorption Layer Based On Surface Microstrcuture

The Terahertz(THz) are electromagnetic wave in the frequency range 0.1~10THz,ranging between millimeter wave and infrared waves. Terahertz radiation has transient,wideband, low-energy, penetration and fear of water characteristics compared to electromagnetic radiation in other bands. THz detector is one of the key components of terahertz science and technology application, and terahertz wave absorbing materials and absorbing structure is a important safeguard for high performance terahertz detector.In this paper, for terahertz absorption studies were designed and prepared by the metamaterial structure and porous rough material.Metamaterial structure as terahertz radiation absorbing layer can efficiently absorb set band of THz radiation, which has been confirmed. However, there are a problem of poor compatibility between this structure and based on micro-bolometer detection unit.In this paper, we designed a metamaterial graph based on micro-bridge structure and optimization and analyzed. In this paper, we designed the square cross metamaterial absorber structure and the size of the unit is 56μm×56μm, and using the CST software to simulate the structures, and through the simulation results we found that the absorption rate is closed to 100 percent at 2.52 THz. By information distribution of electric field, the surface current, power flow and power loss of the metamaterial structure we can see that the electric field distribution of absorption of terahertz radiation at the top of this structure, and absorption frequency of terahertz radiation which is mainly determined by top structure, and power loss of incident terahertz radiation mainly in the dielectric layer. We have also designed metamaterial structure of different sizes and thickness, and using the CST software to simulate the structures, and determine the relationship between the metamaterial structure and the absorption of terahertz radiation.In order to combined metamaterial graphics with micro-bridge structure, we need to reduce the size of the metamaterial graphics. In this paper, we designed a cross structure which top is extended and the size of the unit is 28 um×28 um. Through the simulation results we found that the same frequency is also closed to 100 percent.Meanwhile, we carried out the actual preparation of the metamaterials, and the test results show signification absorption peak at 2.52 THz. We also designed an novelzigzag miniature antenna structure, which has the characteristics of a small size compared with the general dish antenna, and we found that the absorption rate is closed to 100 percent at 2.75 THz. Meanwhile, we carried out the actual preparation of the novel zigzag miniature antenna structure, and the test results show signification absorption peak at 2.75 THz.In the absorption of porous rough surface aspect, we have designed and prepared the single porous silicon structure with DC chemical corrosion. By optimizing the experimental parameters, we are able to prepare a better single layer of porous silicon when the DC current parameters is 0.125 A and etching tome for 20-30 min. When we coated with a layer of NiCr metal thin film which thickness is 20 nm in the single-layer porous silicon structure. This composite structure as terahertz radiation absorbing layer,and through test found that porous silicon and Ni Cr as absorbing layer can achieve absorption rate is closed to 33.5 percent for terahertz radiation.