title: Nanofocusing of hybrid plasmons-phonons-polaritons in a graphene-hexagonal boron nitride heterostructure.
abstract: In this Letter, we investigate the nanofocusing of hybrid plasmons-phonons-polaritons (SPP-HPhPs) in a graphene-hexagonal boron nitride (h-BN) heterostructure with a graphene coating on a tapered h-BN slab. Compared with the hyperbolic phonon polariton (HPhP) in h-BN, the hybrid SPP-HPhP in a heterostructure exhibits much smaller losses, which is validated through both analytical and numerical methods. Furthermore, the thickness dependent dispersions of a hybrid SPP-HPhP enable the tapered heterostructure to achieve a function of focusing electromagnetic waves. Compared with the tapered h-BN slab, the field enhancement in a tapered heterostructure is improved evidently with a maximum enhancement of the amplitude of normalized electric field over 60. This nanofocusing scheme may have potential in applications such as nonlinear optics.
authors.forename: Bofeng
authors.initials: B
authors.lastname: Zhu
authors.forename: Guobin
authors.initials: G
authors.lastname: Ren
authors.forename: Beilei
authors.initials: B
authors.lastname: Wu
authors.forename: Yixiao
authors.initials: Y
authors.lastname: Gao
authors.forename: Haisu
authors.initials: H
authors.lastname: Li
authors.forename: Shuisheng
authors.initials: S
authors.lastname: Jian