Gbps THz external modulator based on the high electron mobility transistor-metamaterial

Utilizing THz waves to transmit data for communication and imaging places high demands in phase and amplitude modulation. Therefore, active devices including modulators and switches have been intensively studied in the THz regime. However, till now these devices still cannot meet the demands of THz systems. In this article we demonstrate an effective, ultra-fast and all electronic grid-controlled THz modulator, which combines an equivalent collective dipolar metamaterial array with an AlGaN/GaN hetero structure. By controlling the carrier concentration of two-dimensional electron gas (2DEG) of the modulator, we realize a resonant mode conversion with blue-shift that significantly improves the modulation speed and depth. This THz modulator achieved 1 GHz modulation speed and 67% modulation depth in real-time dynamic test. Moreover, a 1.19 rad phase shift has also been realized. This active metamaterial modulator can be applied as an effectively and ultra-fast dynamic device in THz wireless communication systems.