Nonlocality induced Cherenkov threshold

Cherenkov radiation is generally believed to be threshold-free in hyperbolicmetamaterials owing to the extremely large photonic density of states in classical localframework. Although recent advances in nonlocal and quantum plasmonics extend ourunderstanding of light-matter interactions in metamater...

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Bibliographic Details
Main Authors: Hu, Hao, Lin, Xiao, Zhang, Jingjing, Liu, Dongjue, Genevet, Patrice, Zhang, Baile, Luo, Yu
Other Authors: School of Electrical and Electronic Engineering
Format: Article
Language:English
Published: 2022
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Online Access:https://hdl.handle.net/10356/154599
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Institution: Nanyang Technological University
Language: English
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Summary:Cherenkov radiation is generally believed to be threshold-free in hyperbolicmetamaterials owing to the extremely large photonic density of states in classical localframework. Although recent advances in nonlocal and quantum plasmonics extend ourunderstanding of light-matter interactions in metamaterials, how such effects influenceCherenkov radiation in hyperbolic metamaterials still remains unknown. Here, it isdemonstrated that effects of nonlocality add a new degree of freedom to engineerCherenkov thresholds in hyperbolic metamaterials. The interplay between finite structuraldimensions and nonlocal nature of metallic electrons results in a nonzero Cherenkovthreshold. Counterintuitively, such nonlocality-induced Cherenkov threshold can besignificantly smaller than the classically predicted one if the metamaterial is designed to workaround the epsilon-near-zero frequency. This phenomenon is attributed to the excitation oflongitudinal plasmon modes which are absent in classical electromagnetic framework. Thesefindings apply to a general class of hyperbolic materials, including metallodielectric layeredstructures, nanorod/nanoribbon arrays, hyperbolic van der Waals crystals, etc.