An electrically-driven terahertz (THz)-wave modulator was numerically designed and experimentally fabricated to realize amplitude modulation of incident THz waves. The THz wave modulator is composed of an array of high electron mobility transistors (HEMTs), an array of split-ring resonators (SRRs), and metal electrodes. Driven by the time-varying gate voltage, the width and thickness of the conducting channel in the HEMT is changed, resulting in the variation in the density of the two-dimensional electron gas (2DEG). With variation of the 2DEG density, the SRR exhibits different transmittance for THz waves. Our measurement results show that~28% modulation depth under an applied gate voltage varying from −3 V to 0 V can be obtained.

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