Recent progress in Fano-resonant terahertz metasurface and its application

The unique electromagnetic response characteristics of metasurfaces and their intrinsic physical mechanisms have attracted a lot of attention. With the help of metasurfaces, the amplitude, phase, polarization, and other information of light waves can be effectively modulated. Fano resonance with asymmetric and sharp line shape is sensitive to refractive index changes in the environment, it can be realized through the structure design of the metasurface. Terahertz wave is located between microwave and infrared waves and can be used in the fields of high-sensitivity detection, high-precision imaging, and wireless communication. Terahertz metasurface with sharp Fano resonance is promising in realizing highly sensitive detection of biological macromolecules, such as glioma cells and other substances, which has attracted more and more attention. Here we review the progress of passive or active terahertz metasurfaces with Fano resonances due to various operation mechanisms and their applications in sensitive sensing.