基于石墨烯结合金属光栅结构的全反射式太赫兹调制器

Terahertz imaging technology has shown great potential in many areas, such as material characterization, biomedical diagnosis and industrial inspections. Most of the published THz imaging systems are using raster scan scheme, which has slow imaging speed; THz detector array can speed up the imaging speed but at a high cost. The newly developed “compressive sensing (CS)” imaging technology has realized single-pixel fast-speed imaging to slove above problems, which utilized a spatial light modulator coding the incident signal in front of the detector. In order to achieve high quality images, the ideal THz spatial light modulator in CS system should contain the advantages of deep modulation depth, high modulation speed and broad operation band. The published THz modulators are incapable of achieving the above three advantages at the same time...In this application, a graphene integrated metal grating THz modulator in total internal reflection geometry has been proposed, which coupled the evanescent wave in total reflection geometry with the metal grating to increase the electric field intensity and realized a deep and fast modulation to the THz signal in a broadband by graphene. In this research, a new theory will be firstly developed to calculate the new system; and then a single pixel modulator will be fabricated; in the end, a 2-D modulator array will be fabricated to spatially modulate the THz signal and realize THz fast-speed imaging.

太赫兹成像技术在材料表征，生物医学诊断和工业检测等领域有广阔的应用前景。目前的太赫兹成像系统多采用逐点扫描方式，这种方式成像速度慢；如果使用太赫兹探测器阵列则制造难度大且价格昂贵。最近发展迅速的压缩感知成像技术可以实现单像素点高速成像，从而解决上述问题，其技术的核心是在探测器前端使用一个可编码的太赫兹空间光调制器。为获得高质量的图像，太赫兹空间光调制器需要具备大调制深度、高调制速度和大工作带宽。目前大多数的太赫兹调制器不能同时满足上述三大要求。.本项目提出的基于石墨烯结合金属光栅结构的全反射式太赫兹调制器将全反射中的表面倏逝波和金属光栅结构对电场的增强作用相结合，利用石墨烯在宽频范围内实现对太赫兹信号的高效，高速调制。本项目首先推导出理论公式用以计算这一模型，然后计划制作出单点调制器并测试，最后扩展成二维阵列实现对太赫兹信号的空间调制，为实现太赫兹高速成像提供解决方案。

太赫兹（Terahertz）一般是指频率在0.1 THz-10 THz（波长3 mm-0.03 mm）范围内的电磁波，太赫兹成像技术在生物医学诊断，工业检测等领域有广阔的应用前景。目前的太赫兹成像系统受制于缺少大规模的探测器阵列而无法实现快速成像。目前的解决方案大多采用压缩感知技术对太赫兹信号进行空间调制，进而在探测端仅使用单点探测器即可实现快速成像。但是，目前的太赫兹电控空间调制器均为窄带工作器件，仅能实现单一频率成像，丢失了样品丰富的太赫兹光谱信号。因此，本项目提出了一种基于全反射光路的金属光栅负载石墨烯的太赫兹电控调制方案，该方案能实现对太赫兹信号的宽带高效调制。本课题的设计方案及制备的器件和方案相比，调制深度提升>30%；和传统的基于超材料的太赫兹调制器相比，调制频率由单一频点扩展为调制带宽>1 THz。本研究还将单点调制器扩展为大规模电控调制器阵列，并研发了阵列调制器对应的外围控制电路，为实现太赫兹成像提供了硬件支撑，对于解决现有的太赫兹成像时间过长，工作带宽过窄等问题具有理论价值和潜在的应用前景。.项目按照计划进度正常执行，实际经费支出与预算基本相符，执行期间项目负责人发表SCI论文7篇，其中中科院JCR1区1篇，2区5篇，3区1篇，申请国家发明专利2项（实审），实用新型专利授权1项，超过预期目标。