Negative refraction in hyperbolic hetero-bicrystals

• 成果类型: Article
• 署名作者: Sternbach, A. J.; Moore, S. L.; Rikhter, A.; Zhang, S.; Jing, R.; Shao, Y.; Kim, B. S. Y.; Xu, S.; Liu, S.; Edgar, J. H.; Rubio, A.; Dean, C.; Hone, J.; Fogler, M. M.; Basov, D. N.
• 署名单位: Columbia University; University of California System; University of California San Diego; Columbia University; Kansas State University; Simons Foundation; Flatiron Institute; Max Planck Society
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-14129
• DOI: 10.1126/science.adf1065
• 发表日期: 2023-02-10
• 页码: 555-557
• 关键词: phonon-polaritons; boron-nitride; index; propagation; light

摘要

We visualized negative refraction of phonon polaritons, which occurs at the interface between two natural crystals. The polaritons-hybrids of infrared photons and lattice vibrations-form collimated rays that display negative refraction when passing through a planar interface between the two hyperbolic van der Waals materials: molybdenum oxide (MoO3) and isotopically pure hexagonal boron nitride (h11BN). At a special frequency co0, these rays can circulate along closed diamond-shaped trajectories. We have shown that polariton eigenmodes display regions of both positive and negative dispersion interrupted by multiple gaps that result from polaritonic-level repulsion and strong coupling.