Active Tuning of Highly Anisotropic Phonon Polaritons in Van der Waals Crystal Slabs by Gated Graphene

Álvarez‐Pérez, Gonzalo; González-Morán, Arturo; Capote‐Robayna, Nathaniel; Воронин, К. В.; Duan, Jiahua; Volkov, Valentyn S.; Alonso‐González, Pablo; Nikitin, Alexey Y.

doi:10.1021/acsphotonics.1c01549

Cited by 48 publications

(29 citation statements)

References 42 publications

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“…Recently discovered phonon polaritons in van der Waals crystals exhibit remarkably low losses [123][124][125]. These phonon polaritons can be tunned through chemical intercalation [126][127][128], twisted stacking [129], and heterostructures [130][131][132][133]. Since the emergence of multiple-input, multiple-output (MIMO) technology for wireless communication, polarization modulation (PoM) has gained more and more attention thanks to its excellent signal distinguishability, thereby increasing spectrum efficiency [134,135].…”

Section: Discussionmentioning

confidence: 99%

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

2022

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The forthcoming sixth generation (6G) communication network is envisioned to provide ultra-fast data transmission and ubiquitous wireless connectivity. The terahertz (THz) spectrum, with higher frequency and wider bandwidth, offers great potential for 6G wireless technologies. However, the THz links suffers from high loss and line-of-sight connectivity. To overcome these challenges, a cost-effective method to dynamically optimize the transmission path using reconfigurable intelligent surfaces (RISs) is widely proposed. RIS is constructed by embedding active elements into passive metasurfaces, which is an artificially designed periodic structure. However, the active elements (e.g., PIN diodes) used for 5G RIS are impractical for 6G RIS due to the cutoff frequency limitation and higher loss at THz frequencies. As such, various tuning elements have been explored to fill this THz gap between radio waves and infrared light. The focus of this review is on THz RISs with the potential to assist 6G communication functionalities including pixel-level amplitude modulation and dynamic beam manipulation. By reviewing a wide range of tuning mechanisms, including electronic approaches (complementary metal-oxide-semiconductor (CMOS) transistors, Schottky diodes, high electron mobility transistors (HEMTs), and graphene), optical approaches (photoactive semiconductor materials), phase-change materials (vanadium dioxide, chalcogenides, and liquid crystals), as well as microelectromechanical systems (MEMS), this review summarizes recent developments in THz RISs in support of 6G communication links and discusses future research directions in this field.

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Section: Discussionmentioning

confidence: 99%

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

2022

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“…However, in all such approaches, only the wavelength of the anisotropic polaritons is directly controlled, yet we envision that similar electromagnetic hybrids can be realized by graphene and biaxial hyperbolic materials in which the polariton propagation direction also changes. For instance, one can potentially change the propagation direction of in-plane hyperbolic polaritons in MoO 3 when a graphene layer is included, 139 while such observations could also be observed by locally changing the carrier density in the vicinity of shear polaritons.…”

Section: ■ Engineering Polariton Anisotropy Through Hybrid Materialsmentioning

confidence: 99%

Anisotropy and Modal Hybridization in Infrared Nanophotonics Using Low-Symmetry Materials

Folland

Duan

et al. 2022

ACS Photonics

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Anisotropy has been a key property employed in the design of optical components for hundreds of years. However, in recent years there has been growing interest in polaritons supported within anisotropic (low crystal symmetry) materials for their ability to compress light to smaller, deeply subwavelength dimensions. While historically the first anisotropic polaritons probed were hyperbolic modes, research into anisotropic materials has recently turned toward hybrid materials and optical modes, employing phenomena such as phonon confinement, polaritonic strong coupling, and Moiré structures to design the optical properties. In this Perspective, we will briefly introduce the physics and theories of polariton anisotropy, review recently investigated anisotropic and two-dimensional materials, and then move on to a discussion of approaches toward realizing hybrid modes and identifying new materials. Based on the results from the past few years, we extend these discussions to highlight outstanding challenges and outline what we perceive as promising paths to further explore the potential for polariton anisotropy and hybrid systems in future nanophotonic optical devices.

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“…Final note: the authors became aware of the following relevant works by Álvarez-Pérez et al 32 ; Bapat et al 33 ; Hu et al 34 ; and Zeng et al 35 after completion of this work.…”

Section: Resultsmentioning

confidence: 97%

Surface plasmons induce topological transition in graphene/α-MoO3 heterostructures

et al. 2022

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Polaritons in hyperbolic van der Waals materials—where principal axes have permittivities of opposite signs—are light-matter modes with unique properties and promising applications. Isofrequency contours of hyperbolic polaritons may undergo topological transitions from open hyperbolas to closed ellipse-like curves, prompting an abrupt change in physical properties. Electronically-tunable topological transitions are especially desirable for future integrated technologies but have yet to be demonstrated. In this work, we present a doping-induced topological transition effected by plasmon-phonon hybridization in graphene/α-MoO3 heterostructures. Scanning near-field optical microscopy was used to image hybrid polaritons in graphene/α-MoO3. We demonstrate the topological transition and characterize hybrid modes, which can be tuned from surface waves to bulk waveguide modes, traversing an exceptional point arising from the anisotropic plasmon-phonon coupling. Graphene/α-MoO3 heterostructures offer the possibility to explore dynamical topological transitions and directional coupling that could inspire new nanophotonic and quantum devices.

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Active Tuning of Highly Anisotropic Phonon Polaritons in Van der Waals Crystal Slabs by Gated Graphene

Cited by 48 publications

References 42 publications

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

Terahertz Reconfigurable Intelligent Surfaces (RISs) for 6G Communication Links

Anisotropy and Modal Hybridization in Infrared Nanophotonics Using Low-Symmetry Materials

Surface plasmons induce topological transition in graphene/α-MoO3 heterostructures

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