Dynamic Tunable Bidirectional Excitation Multi-PIT Device for Terahertz Biosensing and Optical Switching

In this study, a multi-layered and bi-directionally excitable plasmon-induced transparency (PIT) device with multiple graphene layers was designed. The PIT window was regulated by controlling the Fermi level of graphene, resulting in an increase in the resonance frequency and dip depth of the PIT transmission valleys with an increase in the Fermi level. Theoretical investigations were then conducted. Subsequently, the influence of interlayer distance, individual component size, and relative positioning of graphene on the performance of PIT was studied. When employed as a biosensor, it could only be utilized under x-polarized TM waves, exhibiting a maximum sensitivity of 8.2THz/RIU. As an optical switch, it exhibited the highest modulation depth of 89.7% at 9.04THz under x-polarized waves, and a maximum modulation depth of 94.6% at 2.8THz under y-polarized waves. This theoretically designed PIT device can have potential applications in both sensors and optical switches.