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Hyperbolic phonon polaritons (HPhPs) sustained in polar van der Waals (vdW) crystals exhibit extraordinary confinement of long-wave electromagnetic fields to the deep subwavelength scale. In stark contrast to uniaxial vdW hyperbolic materials, recently emerged biaxial hyperbolic materials, such as α-MoO and α-V O , offer new degrees of freedom for controlling light in two-dimensions due to their distinctive in-plane hyperbolic dispersions. However, the control and focusing of these in-plane HPhPs remain elusive. Here, a versatile technique is proposed for launching, controlling, and focusing in-plane HPhPs in α-MoO with geometrically designed curved gold plasmonic antennas. It is found that the subwavelength manipulation and focusing behaviors are strongly dependent on the curvature of the antenna extremity. This strategy operates effectively in a broadband spectral region. These findings not only provide fundamental insights into the manipulation of light by biaxial hyperbolic crystals at the nanoscale but also open up new opportunities for planar nanophotonic applications.
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http://dx.doi.org/10.1002/adma.202104164 | DOI Listing |
Magn Reson Med
September 2025
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
Purpose: To improve single-shot spiral MR-Acoustic Radiation Force Imaging (MR-ARFI)'s robustness to dynamic phase errors and evaluate it in non-human primates (NHPs) with a low-f-number transducer.
Methods: A single-shot spiral MR-ARFI pulse sequence with 2 mm in-plane resolution and alternating displacement phase contrast was implemented to visualize the focus generated by a 128-element ultrasound transducer in the NHP brain. A model-based displacement map calculation was implemented to remove dynamic phase errors.
Nat Commun
August 2025
State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China.
Planar polaritonic lenses, achieved by precisely controlling interface polaritons, hold significant promise for subwavelength light focusing. While most existing designs rely on polariton interference or refraction, creating gradient-index polaritonic lenses remains a substantial challenge due to the lack of practical and cost-effective fabrication methods. Here, we introduce a lithography-free approach for producing polaritonic lenses with gradient effective refractive indices by engineering the dielectric environment of polaritons.
View Article and Find Full Text PDFACS Nano
August 2025
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.
Three-dimensional (3D) chiral metamaterials are structures with broken out-of-plane symmetry. With intrinsic chirality, they present larger circular dichroism (CD) signals than the 2D chiral metamaterials. Among all types of 3D metamaterials, multilayer-stacked metamaterials stand out, as they have the potential for large-scale fabrication.
View Article and Find Full Text PDFA dual-channel reconfigurable metasurface based on vanadium dioxide () and photosensitive silicon is proposed to realize offset focusing and holographic imaging. Based on the Pancharatnam-Berry (PB) phase principle, the three-bit quantization of the cross-reflection phase in the range of 360° is realized by rotating the in-plane mechanism of the unit. Based on the compensated phase formula, focusing theory, and Gerchberg-Saxton (GS) algorithm, the phase distributions of the metasurface are calculated, respectively.
View Article and Find Full Text PDFA reconfigurable three-channel terahertz reflective metasurface based on vanadium dioxide, photosensitive silicon, gold, and silica is proposed. The unit of the metasurface adopts a six-layer sandwich structure, which is mainly designed by the composite resonator on the top layer and the back-to-back double E-shaped structure in the middle layer. Based on the geometric phase principle, through rotating the design pattern in plane, the unit in the range of 360° realizes the 3 bit quantization of the compensation phase of the metasurface's cross reflection.
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