NIR-driven Large Modulation Depth Terahertz Modulator Based on Silver/carbon Nanoparticles

Near-infrared light-driven terahertz modulators are an important component in terahertz/infrared fiber-optic hybrid communication systems. Here, a near-infrared driven terahertz modulator based on silver nanoparticles/carbon quantum dots (Ag NPs/CDs) is proposed. Experimental results show that the combination of silver nanoparticles (Ag NPs) and carbon quantum dots (CDs) induces quantum size effect and dielectric confinement effect of nanoparticles, and the absorption of NIR light by silicon substrate can be enhanced by using Ag NPs/CDs to achieve NIR-driven terahertz wave modulation. The terahertz transmission characteristics of the sample were characterized in the range of 0.22-0. 33 THz with the 808 nm NIR modulation excitation source, and the modulation depth of the Ag NPs/CDs NIR terahertz modulator could reach about 83% compared with the reference silicon substrate, which was significantly higher than the modulation depth of the reference silicon substrate (similar to 54%), realizing the terahertz wave modulation with large modulation depth. This research work has important applications in terahertz/infrared fiber hybrid communication systems.