太赫兹波探测光子晶体涂层覆盖目标的可行性

覆盖于高温目标表面的光子晶体红外涂层可实现对目标红外辐射的抑制,而太赫兹波所具有的强穿透特性使其对该类目标的探测成为可能。以相关文献中设计的光子晶体涂层为例,采用特征矩阵理论对0.3~3 THz频率范围内的太赫兹波在该类涂层中的传输特性进行理论计算和分析,重点研究了不同入射角度的太赫兹波在该类涂层中的传输特性。研究发现,上述太赫兹波段处于光子晶体的带隙之外,0.3~0.5 THz频率范围内的太赫兹波对该类红外涂层具有较强的穿透特性,其光谱透过率大于90%;而在2.4~3 THz范围内,其在涂层上具有较强的反射,且整个波段内的吸收率小于0.2%。当入射角小于60°时,其对太赫兹波的传输特性影响较小;进一步增大入射角,其透过率逐渐降低,而反射率逐渐增大。研究结果证明了利用太赫兹波进行涂层覆盖目标探测的可行性,有望利用太赫兹雷达探测弥补红外探测系统的不足。

Feasibility of Applying Terahertz Wave to Detect Target Covered with Photonic Crystal Coating

The photonic crystal (PC) coating with low transmittance can effectively suppress the thermal radiation of high temperature target.It becomes possible to detect such camouflaged targets applying ternhertz (THz) wave due to the strong penetration capabihty of THz radiation.The propagation characteristics of THz wave in the PC coatings proposed in the references were investigated and analyzed theoretically based on characteristic matrix method of thin-film.The propagation characteristics of THz wave with different incident angles were studied later.The results exhibit that the THz wave ranging from 0.3 to 3 THz does not locate in the band gaps of the PCs.The wave in 0.3 ～ 0.5 THz has strong penetrability to the coating,the spectral transmittance is up to 90％,and the absorptivity over the whole band keeps as low as 0.2％.In addition,the incident angle has relatively little influence on the propagation characteristic when it is less than 60°.With the angle further increasing,the transmittance decreases and the reflectivity is diametrical.The final results demonstrate the feasibility to detect and recognize the targets covered with PC infrared stealth coatings by applying THz wave,and THz radar is promising for use to make up for the deficiency of the infrared detection system.