Broadband and unidirectional plasmonic hyperlensing in drift-biased graphene

• Published in: Applied physics letters 2021-03, Vol.118 (9)
• Main Authors: Paul, N. K., Gomez-Diaz, J. S.
• Format: Article
• Language: English
• Subjects: Applied physics; Broadband; Drift; Emitters; Frequency ranges; Graphene; Green's functions; Plasmonics; Plasmons
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0042580

We suggest and explore the possibility to realize broadband and unidirectional plasmonic hyperlensing over a graphene layer biased with two orthogonal drift-biases. This platform relies on the interplay between nonlocality and nonreciprocity to generate ultraconfined states in the direction aligned with the effective biasing current. The presence of these states shapes, elongates, and significantly flattens the isofrequency contour of the supported modes and enforces the canalization of surface plasmons along the two directions defined by the applied biases. Through a dedicated anisotropic Green's function formalism that takes graphene's intrinsic nonlocality into account, we show that this platform resolves the presence of two point-source emitters with a resolution larger than λ 0 / 500 over a broad frequency range ( ∼ 10 − 25 THz) using realistic biasing schemes. We also discuss how spin–orbit interactions can be exploited to construct unidirectional hyperlenses for near-field images with specific polarization distribution. Our findings may open exciting applications in dynamic, subdiffractive, and planar sensing and imaging systems and in the exciting, routing, and processing of surface plasmons.