Optically pumped terahertz wave modulation in MoS₂-Si heterostructure metasurface

An optically pumped terahertz (THz) modulator based on a MoS₂-Si heterostructure metasurface are fabricated and investigated in this paper. The THz wave modulation in MoS₂ metasurface has been demonstrated by THz time domain spectroscopy experiment and numerical simulation, which can reach over 90% under the continuous wave laser pumping of 4W/cm² power density. Importantly, the catalysis of photocarrier generation in MoS₂-Si heterostructure has been proved by the comparsion between the modulation depth of metasurface with and without MoS₂ nanosheet under the same pumping power, and we found that the strcuture of metasurface and polariztion direction can also influence the photocarrier density in MoS₂ metasurface. This novel THz modulator based on 2D material has a high effective modulation on THz waves under a low pumping power, which has a bright potential in THz applications.