Electrically reconfigurable micromirror gratings for direct spatial modulation of terahertz waves and hyperspectral terahertz imaging over a wide frequency range

该项目旨在设计、制造大口径、电可调谐的直接空间太赫兹波调制器，以实现太赫兹编码孔径成像光谱仪中的高光谱成像。该调制器的设计频率在0.5 THz到2.5 THz之间，并应在所需的频率范围内提供约1 THz的光谱工作带宽。调制器的像素应由长度至少为200μm的微镜阵列组成。根据微镜的倾角，调制器的象素是暗的还是亮的。对于空间太赫兹波调制，不同像素的微镜必须通过施加偏置电压来单独切换。为了设计大口径空间太赫兹波调制器，需要对这种基于微镜的光栅调制器的设计和制作进行优化。为此，将亚表面作为透明接地电极的集成是否能在频率工作范围内改善调制对比度将是一个值得研究的问题。在进一步的研究中，我们将利用光栅调制和超材料吸收相结合的方法来扩展空间太赫兹波调制器的工作频率范围，并在此基础上设计和实现一个大口径、宽频带的空间太赫兹波调制器。大口径调制器将用于编码孔径成像光谱仪中的空间光调制，用它来演示带宽为1 THz的光谱宽带高光谱太赫兹成像。

The project aims at the design, fabrication and theoretical andexperimental investigation of large-aperture, electrically tunable, directspatial terahertz wave modulators that enable hyperspectral imaging in a terahertzcoded aperture imaging spectroscope.The modulators are designed for frequencies between 0,5 THz und 2,5 THz and shall provide a spectral working bandwidth of about 1 THz within the desired frequency range. The pixels of the modulators shall be composed of an array of micromirrors with a length of at least 200 μm. Dependent on the inclination angle of the micromirrors, apixel of the modulator appears dark or bright. For spatial terahertzwave modulation, the micromirrors of the different pixels must beindividually switched by application of a bias voltage. In order todesign a large-aperture spatial terahertz wave modulator, it isnecessary to optimize both the design and the fabrication of suchmicromirror-based grating modulators. For this reason, it will be investigated ifthe integration of metasurfaces as transparent ground electrodes canimprove the modulation contrast within the frequency working range. In a further approach, grating modulation and metamaterial-based absorption will be combined to extend the frequency working range of the spatial terahertz wave modulator.Based on the project results, a large-aperture, spectrally wide-band spatial terahertz wave modulator will be devised and implemented. The large-aperture modulator willbe used for spatial light modulation in a coded aperture imagingspectroscope, with which spectrally wideband hyperspectral terahertzimaging with a bandwidth of 1 THz shall be demonstrated.