Phase mismatch induced suppression of eigenmode resonance in terahertz metasurfaces.

In this paper, we observe the distinguishable modulation of the different eigenmodes by lattice mode in terahertz U-shaped metasurfaces, and a remarkable lattice induced suppression of the high order eigenmode resonance is demonstrated. With the quantitative analysis of Q factor and loss of the resonances, we clarify that the peculiar phenomenon of suppression is originated from the phase mismatch of the metasurfaces via introducing the phase difference between the neighboring structures. These results provide new insights into the phase mismatch mediated transmission amplitude of eigenmode resonance in metasurfaces and open a new path to developing terahertz multifunctional devices.

Design and analysis of terahertz filters based on multilayer metamaterials.

We numerically and experimentally demonstrate a series of multilayer metamaterial filters in the terahertz region. The designed structure consists of multiple metal-polyimide composite layers and cyclic olefin copolymer layers. The transmission spectra of the filters are characterized by terahertz time-domain spectroscopy, and the measured results agree well with simulations. In addition, the mechanism of the multilayer structure is theoretically studied by a thin film multibeam interference model. The proposed filters exhibit high efficiency at passband and can be broadly utilized as compact devices in practical applications at terahertz frequencies.

Terahertz multi-level nonvolatile optically rewritable encryption memory based on chalcogenide phase-change materials.

Fast and efficient information processing and encryption, including writing, reading, and encryption memory, is essential for upcoming terahertz (THz) communications and information encryption. Here, we demonstrate a THz multi-level, nonvolatile, optically rewritable memory and encryption memory based on chalcogenide phase-change materials, Ge2Sb2Te5 (GST). By tuning the laser fluence irradiated on GST, we experimentally achieve multiple intermediate states and large-area amorphization with a diameter of centimeter-level in the THz regime. Our memory unit features a high operating speed of up to 4 ns, excellent reproducibility, and long-term stability. Utilizing this approach, hexadecimal coding information memories are implemented, and multiple writing-erasing tests are successfully carried out in the same active area. Finally, terahertz photoprint memory is demonstrated, verifying the feasibility of lithography-free devices. The demonstration suggests a practical way to protect and store information and paves a new avenue toward nonvolatile active THz devices.