Dynamic control of the terahertz rainbow trapping effect based on a silicon-filled graded grating*

We theoretically propose a scheme to realize the dynamic control of the properties of the terahertz (THz) rainbow trapping effect (RTE) based on a silicon-filled graded grating (SFGG) in a relatively broad band via optical pumping. Through the theoretical analysis and finite-element method simulations, it is conceptually demonstrated that the band of the RTE can be dynamically tuned in a range of ~0.06 THz. Furthermore, the SFGG can also be optically switched between a device for the RTE and a waveguide for releasing the trapped waves. The results obtained here may imply applications for the tunable THz plasmonic devices, such as on-chip optical buffers, broad band slow-light systems, and integrated optical filters.