Ultra-confined low-loss surface phonon polaritonic resonances in periodically patterned monolayer hexagonal boron nitride

Abstract Surface plasmon polaritons in two-dimensional (2D) materials such as graphene have drawn much attention in the past decades, nevertheless, suffer from ohmic losses. Recently, monolayer hexagonal boron nitride (hBN) has been found the capability to support low-loss surface phonon polaritons (SPhPs). In this work, we theoretically propose the atom-thin metasurface with monolayer-hBN. We reveal that monolayer-hBN disk array can support SPhP resonances with ultra-small effective mode volumes (~10 −9 λ03 ) as well as high quality factors (10 2-103) in mid-infrared (mid-IR). The corresponding frequency dispersions with geometrical parameters and ambient environment are also discussed in detail. Furthermore, the phenomenon of phonon hybridization is demonstrated based on monolayer-hBN ring array. Finally, the local field enhancement with an enhancement factor ~103 is realized by breaking the symmetry of the ring. This work reveals that monolayer-hBN can play an important role in 2D material polaritonics and atom-thin metasurfaces, and has great potential in mid-IR quantum emission, sensing and spectroscopic applications.