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

• Applicant: Professor Dr. Marco Rahm
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology ; Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458851938

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.

• DFG Programme: Research Grants