In addition, another deficiency is

In addition, another deficiency is that the drawing-voltage of THz graphene modulators isgenerally as high as several tens of volts [13,17]. Given all these dynamic devices are controlled bymanipulating the carrier concentration of graphene, enhancing doping efficiency will be a crucial pointto realize deep tunable elements with low voltage. Compared with conventional materials adopted, thesolid electrolyte is one of the attractive options for high-capacity donors applied in THz. For instance,the capacitance of solid electrolyte (10 µFcmm 2) is ≈800 times higher than that of the 300 nm SiO2plate capacitor [18–20]. Moreover, unlike high-k dielectrics (1 to 2 µFcmm 2) [21–26], solid electrolyteswould not have problems due to the strict constraints of the growth environment or the processingconditions [27]. Aside from this, it was reported that the solid electrolyte also had superior advantagesincluding transparency, good mechanical flexibility, fatigue stability, electrochemical, and thermalstability [28–30].In this work, we propose an effective THz configuration comprised of metamaterials,solid electrolyte, and graphene to realize dynamical modulation of device transmittance. By using thesolid electrolyte top gate, we can obtain a highly doped graphene membrane with activity tunablecarrier densities via small gate voltage. Moreover, it has been experimentally verified that a maximumMD of 53% is achieved within 5 V of gate voltages with this device. Besides, the fabrication ofthis device demands inexpensive equipment. This architecture provides a feasible approach foroptimizing THz active modulation performance with single-layer graphene. Additionally, because theflower-shaped structure in this work is considered a kind of customized metamaterial, it could bereplaced corresponding to a specific application in the future.