Abstract
Terahertz modulators with capability of both intensity and phase are essential for THz imaging and communication systems. The low-voltage driven THz modulation technique is crucial for integrating the modulators with electronics components. There is still a lack of broadband devices able to achieve both amplitude and phase modulation with low voltage, due to the underlying physics behind existing approaches. Here, we demonstrate a graphene-loaded metal wire grating THz modulator in the total internal reflection geometry to achieve intensity modulation of 80% and phase modulation of 70 degree within 3 volts gate voltage. Quite different from using the strategy of metamaterials based on the electromagnetic resonance effects, our design has performed a broadband modulation for over 1 THz bandwidth.
Highlights
In the past decade, terahertz (THz) technology has shown its potential in many areas, e.g. biomedical imaging [1,2,3], material characterization [4,5,6] and high-speed wireless communications etc. [7, 8]
The Al2O3/Si gated device was measured in the transmission configuration to calculate its modulation depth (MD) first; the polarization of the incident THz light was perpendicular to the metal wire grating (Fig. 2(a))
The time-domain signal in transmission geometry decreases gradually as the applied gate voltage tuned from -3 V to 3 V, which indicates the conductivity of graphene is increased
Summary
Terahertz (THz) technology has shown its potential in many areas, e.g. biomedical imaging [1,2,3], material characterization [4,5,6] and high-speed wireless communications etc. [7, 8]. Terahertz (THz) technology has shown its potential in many areas, e.g. biomedical imaging [1,2,3], material characterization [4,5,6] and high-speed wireless communications etc. It is still a great challenge to modulate THz signal to achieve both high modulation depth (MD) and broadband response with a single device. As its conductivity can be tuned by an external voltage, is heralded as one of the extremely important 2D materials in optoelectronic devices [12], so it has attracted great attention in the THz region [13, 14]. The first demonstration of graphene-based THz modulator was report by Rodriguez et al, which achieved a ~15% intensity
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