Broadband and large-depth terahertz modulation by self-assembly monolayer silver nanoparticle arrays

Broadband and large-depth THz modulation are crucially important for building next-generation THz devices in THz communication systems. Here, we present a broadband and large-depth THz modulator based on silicon/self-assembled silver nanoparticle (SAM AgNP) arrays, which exhibits a broadband modulation within the frequency range of 0.2-2.0 THz and a large modulation depth of ∼91.2% under a moderate near-infrared (NIR) light intensity of 1.77 W cm−2. For a modulation mechanism, the plasmon-enhanced NIR light absorption of SAM AgNP arrays shows a key role in increasing the photoconductivity of the device under NIR light irradiation. The experimental results are verified well by the numerical simulation. The proposed device can significantly improve the overall performance of THz systems, and opens the opportunity for designing novel nanoparticle-based THz devices.