Electrically tunable transmission characteristics in the type-I band based on grating graphene/h-BN heterostructures

The graphene/h-BN heterostructures exhibit a unique plasmon-phonon polaritons coupling mode in the mid-IR frequency spectrum, with adjustable excitation intensity through external voltage. Such an innovation opens up avenues for designing low-power, subwavelength, and electrically tunable devices. A grating structure is introduced in this paper to overcome the constraints posed by previous probe-based methods for wavevector matching. The grating structure simplifies the experimental setup, enhancing the practicality and scalability of the heterostructures. Furthermore, an investigation is conducted into the optical properties and electrical tunability of the grating-integrated graphene/h-BN heterostructures. Numerical simulations and theoretical calculations reveal remarkable electrical tunability of optical transmission characteristics in the type-I band, especially at an incident frequency of 23.816 THz. As external voltage increases, the dispersion curve undergoes a noticeable red shift, reaching a maximum negative absorptivity of -207.36% at 5 V, with reflectivity decreasing to 4.60%. Electric field distribution maps indicate a substantial enhancement in electric field intensity within graphene/h-BN/graphene parts of the structure at 5 V, with the change in electric field direction primarily contributing to the negative absorption. Additionally, the transmittance spectrum confirms the effective modulation of 23.816 THz light transmissivity through adjustments in external voltage, with values of 22.14% at 4 V and 302.77% at 5 V, respectively. The findings provide a foundation for applying graphene/h-BN heterostructures in integrated photonic systems, light manipulation, optical sensing and other fields.