Optically controllable terahertz modulator based on electromagnetically-induced-transparency-like effect

An optically controllable terahertz wave modulator based on the electromagnetically induced transparency-like effect (EIT-like) of the metamaterial structures is proposed and demonstrated. A modulation depth of 63% was measured at 0.33 THz in our study. The modulation action arises from the destructive interference between the resonators composed of high-resistivity silicon and gold resonators. Utilizing terahertz time domain spectrometer (THz-TDS), we show that the transmission properties of the structures can be tuned by an externally applied pump beam. By comparing the modulation depth with and without the structures producing EIT-like behavior, and the bare silicon's modulation depth, it is found that the modulation performance can be significantly improved with employment of EIT effect. Our study provides an alternative route to facilitate potential applications in terahertz range.