Low terahertz frequency on-chip multi-functional modulator with amplitude and phase modulation

Abstract Terahertz amplitude and phase modulation technologies are crucial for terahertz communication, radar, and imaging. However, most current approaches can only achieve either amplitude or phase modulation. In this paper, we present a low terahertz frequency on-chip multi-functional modulator that consists of a hybrid coupler and reflection meta-structure. High-performance amplitude modulation is achieved by combining series resonant absorption of series coupling branch (SCB) with resonance enhancement of parallel coupling branch (PCB) in the reflection meta-structure. Meanwhile, the enhanced resonance provides a larger range of phase shifts, enabling effective amplitude and phase modulation in two different frequency regions. Therefore, we realize an amplitude modulation in the range of 115-135 GHz with a minimum transmission loss of 4 dB and a modulation depth of over 10 dB. At the same time, we achieved a continuous phase shift in the 103-113 GHz region, as well as a 180-degree 2-bit phase shift in the 107-109 GHz range with only 5.7 dB transmission loss. Our simple method for terahertz amplitude and phase multi-functional modulation offers the potential to construe terahertz multifunctional integrated systems.