All-Optically Controlled Terahertz Modulation by Silicon-Grown CdSe/CdZnS Colloidal Quantum Wells

The CdSe/CdZnS colloidal quantum wells, with their exceptionally high carrier mobility and ultrafast response characteristics, emerge as highly promising candidate material for high-performance active terahertz modulators-indispensable core components critical for next-generation communication technologies. A high-performance, cost-effective terahertz modulator was fabricated through spin-coating CdSe(4ML)/CdZnS nanosheets onto a silicon substrate. This all-optical device demonstrates broadband modulation capabilities (0.25-1.4 THz), achieving a remarkable modulation depth of 87.6% at a low power density of 2 W/cm^2. Demonstrating pump-power-efficient terahertz modulation characteristics, this core-shell composite shows immediate applicability in terahertz communication systems and non-destructive testing equipment.