Unidirectionally excited phonon polaritons in high-symmetry orthorhombic crystals

Zhang, Qing; Ou, Qingdong; Si, Guangyuan; Hu, Guangwei; Dong, Shaohua; Chen, Yang; Ni, Jincheng; Zhao, Chen; Fuhrer, Michael S.; Yang, Yuanjie; Alù, Andrea; Hillenbrand, Rainer; Qiu, Cheng‐Wei

doi:10.1126/sciadv.abn9774

Cited by 26 publications

(23 citation statements)

References 43 publications

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“…[ 39a,103 ] With the development of optical nanostructures and active materials, the optical field will be greatly manipulated to realize prototype devices such as in‐plane negative refraction and in‐plane metalenses (e.g., Figure 6e). [ 37b ] In addition, the unidirectional propagation of polariton can also be manipulated by means of a 1D grating structure, [ 104 ] which provides a new dimension to control the polariton propagation. The twisted vdWHs have also showcased interesting features for modulating the polariton propagation, contributing to the novel photonic devices such as a natural plasmon photonic crystal 26 …”

Section: Perspectivesmentioning

confidence: 99%

Polaritons in Van der Waals Heterostructures

et al. 2023

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Tunable nanophotonic systems that can be integrated with silicon and manipulate light at deep-subwavelength scales is of paramount importance for photonic integrated circuits, [1] enhanced light-matter interaction, [2] sub-diffraction imaging, [3] metamaterials, [4] and negative refraction [5] among other feats. In particular, polaritons in 2D materials exhibit the highest degree of mode confinement. [6] A variety of highly confined polaritons with unique properties [6,7] have been demonstrated in 2D materials, for example, electrically tunable plasmons in graphene, [7a,8] ultralow-loss phonon polaritons in hexagonal boron nitride (h-BN) [9] and α-MoO 3 , [7c,7d] room-temperature exciton polaritons in MoSe 2 , [10] WSe 2 [11] and CsPbBr 3 microsheets, [12] and Cooper-pair polaritons. [13] These surface modes have prompted the exploration of multiple potential applications, such as surface-enhanced infrared spectroscopy, [8a,14] optical sensors, [15] nanolasers, [16] light modulators, [17] and nanophotonic circuits. [18] However, in most practical applications, important challenges, such as relatively large optical losses, reduced operation frequency range, and slow modulation speed, are remaining.The hybrid light-matter nature of polaritons (i.e., quasiparticles made up of a photons coupled to polarization charges in a material) can be passively tuned by designing the composition and geometry of the hosting materials, [9,19] offering important advantages for nanophotonic systems. [6a,20] Recently, van der Waals heterostructures (vdWHs), which can be fabricated by exfoliating 2D materials down to isolated monolayers and subsequently reassembling them in a layer by layer fashion in precisely chosen compositions, stacking sequence, and twist angles, provide a versatile way to customize polaritons. [21] For example, an ultralong lifetime graphene plasmon in graphene/h-BN vdWHs, [7a,22] an efficient all-optical modulation of graphene plasmons in the graphene/ monolayer MoS 2 vdWHs, [23] a strong plasmonic nonlinear response in graphene/metal heterostructures [24] have been demonstrated. Moreover, the behavior of polaritons can also be modulated by creating moiré patterns in the vdWHs, such that one can obtain, for example, an extremely long plasmon lifetime (≈3 ps) in stacked bilayer graphene, [25] photonic crystals of twisted bilayer graphene (TBLG), [26] and tunable topological transitions of phonon polaritons in twisted α-MoO 3 bilayers. [27] 2D monolayers supporting a wide variety of highly confined plasmons, phonon polaritons, and exciton polaritons can be vertically stacked in van der Waals heterostructures (vdWHs) with controlled constituent layers, stacking sequence, and even twist angles. vdWHs combine advantages of 2D material polaritons, rich optical structure design, and atomic scale integration, which have greatly extended the performance and functions of polaritons, such as wide frequency range, long lifetime, ultrafast all-optical modulation, and photonic crystals for nanoscale light. Here, th...

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Section: Perspectivesmentioning

confidence: 99%

Polaritons in Van der Waals Heterostructures

et al. 2023

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“…In α-MoO3, Zhang et al patterned linear gratings, which couple with the in-plane anisotropy of α-MoO3, leading to symmetry breaking of the momentum matching in the polariton grating diffraction, as shown in Fig. 20(a) [304] . The polariton diffraction occurs in the condition of Λ cosθ=mλP, where Λ is the period of the grating, θ is the diffraction angle, and λP is the wavelength of polaritons.…”

Section: Polaritons Of Anisotropic 2d Materialsmentioning

confidence: 99%

“…Bidirectional propagation is observed in gratings with circular holes, and unidirectional propagation is observed in blazed gratings. (c) (bottom) Fourier transform of the images in the middle panels [304] .…”

Section: Polaritons Of Anisotropic 2d Materialsmentioning

confidence: 99%

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Optical properties and polaritons of low symmetry 2D materials

et al. 2023

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Low symmetry 2D materials with intrinsic in-plane anisotropic optical properties and high tunability provide a promising platform to explore and manipulate light-matter interactions. To date, dozens of in-plane anisotropic 2D materials with diverse band structures have been discovered. They exhibit rich optical properties, indicating great potential for novel applications in optics, photonics, and optoelectronics. In this paper, we thoroughly review the anisotropic optical properties and polaritons in many kinds of low symmetry 2D materials, aiming to elicit more research interest in this field. First, the optical properties of anisotropic 2D semiconductors, including interband absorption, photoluminescence, excitons, and band structure engineering for tuning optical responses, are introduced. Then fundamentals and advances in experiments of hyperbolic polaritons in anisotropic 2D materials, including phonon, plasmon, and exciton polaritons, are discussed. Finally, a perspective on promising research directions is given.

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“…22,23 In particular, the discovery of hyperbolic shear polaritons (HShPs) in monoclinic b-Ga 2 O 3 further inspires new directions for nanophotonics in low-symmetry materials. [23][24][25][26] The HShPs are a new class of polariton modes, and were first proposed and experimentally confirmed by N. C. Passler et al in 2022. 23 They emerge in crystalline materials in which the permittivity tensor cannot be diagonalized.…”

Section: Introductionmentioning

confidence: 95%