BST-silicon hybrid terahertz meta-modulator for dual-stimuli-triggered opposite transmission amplitude control.

With the drafting of the 6G white paper, terahertz (THz) modulators reshow profound significance in wireless communication, data storage, and imaging. Active tuning of THz waves through hybrid meta-structure incorporated with smart materials has attracted keen interest due to the deliberate structural design and dynamic transition of material properties. However, until now, these meta-devices have usually been responsive to a single driving field, such as electrical, thermal, or optical stimuli, which hinders their applicability for multidimensional manipulation of THz waves. Herein, to the best of our knowledge, a BaSrTiO-silicon hybrid meta-modulator to achieve opposite tuning of the amplitude characteristic with two different types of stimuli is proposed for the first time. When driven by an external voltage, the proposed meta-modulator exhibits enhanced transmittance. In contrast, the transmission coefficient gradually decays as the external current increases. This outstanding performance is systematically studied by analyzing the carrier transport in the meta-structure as well as the change in the dielectric constant. Our research provides a novel idea for the development of actively tunable THz meta-devices and paves the way for robust multifunctionality in electrically controlled THz switching, and biosensors.