微型化亚太赫茲超材料发射器的研究

Recently, electromagnetic waves in the sub-terahertz (sub-THz) frequency range have received tremendous research attention. This spectral range (frequencies between approximately 0.1 and 1 THz) is of special interest for widespread applications because many substances have a specific spectral response in this frequency interval. The continued interest in sub-THz research demands high power sources and sensitive detectors because the energy of photons in sub-THz range is relatively low. Imaging system in this spectral range generally requires an illumination source due to the lack of appreciable background thermal radiation. "Metamaterials" are artificially made electromagnetic materials consisting of periodically arranged metallic elements which are less than wavelength of incident electromagnetic wave in size. Moreover, metamaterials can exhibit the thermal generation of narrowband infrared by controlling emissivity, which may provide novel tools to significantly generate the sub-THz radiation. Metamaterial emitter at sub-THz spectral region has been demonstrated and seems to be a promising direction of the future for wide range of sub-THz applications. In this project, we propose four tasks for developing sub-THz emitters. Firstly, a sub-THz metamaterial narrowband emitter will be explored on spectral emissivity. Secondly, we will design novel metamaterial designs with different pattern size in out-of-plane direction as a single unit cell to provide broadband emission. Thirdly, we will use stressed beam concept to demonstrate a MEMS-based sub-THz metamaterial emitter to achieve longer tuning range and faster speed. Finally, we will deliver a miniaturized metamaterial emitter with potential monolithic integration with CMOS IC process. Therefore, we can demonstrate single narrow band, multiple narrow bands and broadband emitters with active control on the chip-level. In the future, the MEMS-based sub-THz metamaterial emitters can be not only used in the optical, biological, medical and imaging system, but also used in high-speed communication system, portable spectroscopy and various sensors applications.

近年来，亚太赫兹(0.1-1 THz)电磁波引起了广泛的科研关注。由于亚太赫兹的光子能量很低，需要高功率光源与高敏感侦测器以满足实际应用。现行的光源通常体积庞大且能耗高，难以实现小型件微型化。经实验证实，采用超材料结构可产生窄频红外线光源，这为产生亚太赫兹辐射提供了新方法。应用此物理原理，本课题提出了一种MEMS窄频亚太赫兹发射器(光源)，并进一步与微加热器进行单片集成。该器件具有微型化、成本低、调变范围大、响应时间短、与CMOS制程兼容等优点，可广泛应用于无线高速通讯(200-300GHz)系统、可携带式光谱仪系统和各式类型的微感测器。

近年来，亚太赫兹电磁波引起了广泛的科研关注。由于亚太赫兹的光子能量很低，需要高功率光源与高敏感侦测器以满足实际应用。现行的光源通常体积庞大且能耗高，难以实现小型件微型化。经实验证实，采用超材料结构可产生窄频红外线光源，这为产生亚太赫兹辐射提供了新方法。本项目将微机电技术中的悬臂梁与太赫兹超材料相结合，设计、制作并测试了以单一悬臂梁为基础单元的超材料结构，探索了不同几何形状、尺寸与材料对于太赫兹频谱的影响，并研究了其近场电磁波模式分布，实现了可调变的亚太赫兹发射器。这一发射器具有的微型化、成本低、调变范围大、响应时间短、与CMOS制程兼容的优点。在此基础之上，本项目设计了基于多个悬臂梁的开口谐振环、八角环形等超材料结构，研究了其在带宽调制、电磁感应透明效应、动态开关和二进制数字编码等方面的应用。我们进一步提出了基于钼-氮化铝-钼这一新材料平台的超材料吸收体。这一新平台具体可以与CMOS制程兼容和耐400度高温的优点，将其和传统二氧化硅平台对比，确认了它在高温下的稳定性及作为亚太赫兹发射器的能力。最后，将超材料结构和微流体技术集成，实验验证了其捕捉探测20 μm粒子和检测生物成分三磷酸腺苷的能力。本项目对基于微机电技术的可调太赫兹超材料平台做了系统深入的理论与实验探索，为将来的太赫兹集成芯片提供了经验。