Review About the Optical-Controlled Terahertz Waves Modulator

A review of optical-controlled modulators in terahertz regime is presented. Regular semiconductor materials and organic materials at the terahertz frequencies enable fascinating modulation behaviors, including frequency shift and phase and amplitude modulation, observed in devices of subwavelength dimensions. Modulation enhancement was realized by changing the carrier concentration of the local or whole surface in arrays of various structure cells involved with split-ring resonators, holes, and apertures. We also illustrate some new methods to realize modulation for electromagnetic waves. Optical-controlled modulators and the novel manipulation methods will find amazing applications in terahertz communication, imaging, and sensing.