Terahertz wave phase modulator based on GaN HEMT-Metamaterial

In this paper, we demonstrate that efficient phase modulation of THz wave can be addressed by active and enhanced resonant GaN high electron mobility transistor (HEMT) array metamaterials. We exploit the large phase shift of THz wave by using an enhanced resonant metamaterial structure which couples the traditional dipolar and inductance-capacitance resonances. By electrical controlling of the carrier distribution and depletion of the 2 dimensional electron gas (2DEG) in the HEMT array, the resonance intensity and surface current circuit of the enhanced resonant mode in the structure can be dynamic manipulated which realizes more than 150 degree phase shift in simulation. In the dynamic experiment, a 130 degree phase shift can be achieved with only several volts external voltage in the THz transmission mode. Moreover, more than 100 degree phase modulation can be obtained with 20GHz bandwidth. This concept provides a promising way to develop the fast and effective phase modulator in THz application system.