Active terahertz wave modulator based on molybdenum disulfide

A high-efficiency active terahertz wave modulator based on a molybdenum disulfide (MoS2)/germanium (Ge) structure was investigated. Spectrally broadband modulation of the THz transmission was obtained using optical control over the frequency range from 0.2 to 2.6 THz. The MoS2 monolayer structure on germanium demonstrated enhancement of the terahertz modulation depth when compared with those of bare Ge and the graphene/Ge structures. The results show that the MoS2-based modulator demonstrated even higher modulation efficiency than the graphene-based device. The modulation enhancement mechanism that originated from increased conductivity was analyzed. The optical modulation properties of the MoS2/Ge device show tremendous promise for applications in terahertz modulation and switching.