In this paper, a tunable multilayer structure is proposed, which can provide reversible switching between transmission and absorption modes at the terahertz region without reconfiguration. The layered structure consists of graphene, Si, and VO2 layers. Transfer matrix method is employed to describe the optical properties of the layered structure. The switching phenomenon occurs based on the VO2 transition from insulator to metal phase by varying temperature. Furthermore, active frequency tuning by graphene chemical potential for thermally switching transmission and absorption with near-perfect intensity is observed. Incidence angular stability for TE and TM is up to $20^\circ $ and $40^\circ ,$ respectively. Finally, the Si layer thickness effect demonstrates that mainly defines the peak number and frequency for both functions. Theoretical implementation confirms the potential usefulness of the proposed configuration in applications such as reversibly tunable smart absorbers, filters, or thermo-optical switches for high-speed optical systems.
