Ultra-broadband Terahertz Complex Amplitude Modulation by HEMT-Switch Control 1-bit Coding Microstructure

In this paper, an electronically controlled terahertz 1-bit complex amplitude modulation by OOK (on-off-keying) resonance shifting on an array of coplanar elementary HEMTs (high electron mobility transistors) is proposed. The effects of dispersion characteristics on the phase shift and amplitude characteristics are investigated for different two-dimensional electron gas concentrations. A broadband reflection phase shift of 180 degrees and an average amplitude of -3.3 dB were achieved within 0.327-0.353 THz at low switching rates. For the current state of the art analysis, the proposed hybrid microstructure is capable of reprogrammable modulation of the wavefront, which is sufficient to demonstrate the feasibility of ultrafast terahertz wavefront modulation.