Intrinsic restoring enabled mode-selective frequency shifts in self-referenced humidity sensing

Plasmon-induced transparency (PIT) offers a promising route for enhancing light-matter interactions. However, in existing studies, the dynamic tuning of PIT exhibits an overall frequency-shift trend with changes in graphene carrier mobility. This paper proposes a periodic array composed of Π-shaped graphene and graphene strips, achieving a triple PIT through a composite mechanism of destructive interference between bright and dark modes and coupling between bright modes. Research demonstrates that as carrier mobility increases, the four transmission dips exhibit significant selective frequency shifts, with the first one remaining particularly stable. This is attributed to dip1 being primarily dominated by the dark mode, whose inherent tendency to blue-shift counteracts the red-shift trend induced by increasing carrier mobility. The composite mechanism generating the triple PIT provides inspiration for the design of self-referencing optical humidity sensors (0.49 GHz/%RH).