Surface polaritons, which are electromagnetic waves coupled to material charge oscillations, have enabled applications in concentrating, guiding and harvesting optical energy below the diffraction limit. Surface plasmon polaritons involve oscillations of electrons and are accessible in noble metals at visible and near-infrared wavelengths, whereas surface phonon polaritons (SPhPs) rely on phonon resonances in polar materials, and are active in the mid-infrared. Noble metal surface plasmon polaritons have limited applications in the mid-infrared. SPhPs at flat interfaces normally possess long polariton wavelengths and provide modest field confinement/enhancement. Here we demonstrate propagating SPhPs in a one-dimensional material consisting of a boron nitride nanotube at mid-infrared wavelengths. The observed SPhP exhibits high field confinement and enhancement, and a very high effective index (neff~70). We show that the modal and propagation length characteristics of the SPhPs may be controlled through the nanotube size and the supporting substrates, enabling mid-infrared applications.
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http://dx.doi.org/10.1038/ncomms5782 | DOI Listing |
Discov Nano
January 2025
LIMMS, CNRS-IIS IRL 2820, The University of Tokyo, Tokyo, 153-8505, Japan.
We demonstrate unprecedented control and enhancement of thermal radiation using subwavelength conical membranes of silicon nitride. Based on fluctuational electrodynamics, we find that the focusing of surface phonon-polaritons along these membranes enhances their far-field thermal conductance by three orders of magnitude over the blackbody limit. Our calculations reveal a non-monotonic dependence of the thermal conductance on membrane geometry, with a characteristic radiation plateau emerging at small front widths due to competing effects of the polariton focusing and radiative area.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, School of Materials Science and Engineering, Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Xi'an, 710072, P. R. China.
Mn ions doped CsPbCl perovskite nanocrystals (NCs) exhibit superiority of spin-associated optical and electrical properties. However, precisely controlling the doping concentration, doping location, and the mono-distribution of Mn ions in the large-micro-size CsPbCl perovskite host is a formidable challenge. Here, the micro size CsPbCl perovskite crystals (MCs) are reported with uniform Mn ions doping by self-assembly of Mn ions doped CsPbCl perovskite NCs.
View Article and Find Full Text PDFNanophotonics
January 2025
Departamento de Ingeniería Electrónica, E.T.S.I. de Telecomunicación, Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), Universidad Politécnica de Madrid, Madrid, 28040 Spain.
Polar biaxial crystals with extreme anisotropy hold promise for the spatial control and the manipulation of polaritons, as they can undergo topological transitions. However, taking advantage of these unique properties for nanophotonic devices requires to find mechanisms to modulate dynamically the material response. Here, we present a study on the propagation of surface phonon polaritons (SPhPs) in a photonic architecture based on a thin layer of α-MoO deposited on a semiconducting 4H-SiC substrate, whose carrier density can be tuned through photoinduction.
View Article and Find Full Text PDFSmall Methods
January 2025
NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Pisa, I-56127, Italy.
A ground-breaking graphene-based biosensor designed for label-free detection of immunoglobulin M (IgM) achieving a remarkable concentration of 100 zeptomolar (10 m), is reported. The sensor is a two-terminal device and incorporates a millimeter-wide gold interface, bio-functionalized with ≈10 anti-IgM antibodies and capacitively coupled to a bare graphene electrode through a water-soaked paper strip. In this configuration, few affinity binding events trigger a collective electrostatic reorganization of the protein layer, leading to an extended surface potential (SP) shift of the biofunctionalized Au surface.
View Article and Find Full Text PDFNat Commun
January 2025
Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao, China.
The development of acid-stable water oxidation electrocatalysts is crucial for high-performance energy conversion devices. Different from traditional nanostructuring, here we employ an innovative microwave-mediated electron-phonon coupling technique to assemble specific Ru atomic patterns (instead of random Ru-particle depositions) on MnCrO surfaces (Ru-MnCrO) in RuCl solution because hydrated Ru-ion complexes can be uniformly activated to replace some Mn sites at nearby Cr-dopants through microwave-triggered energy coherent superposition with molecular rotations and collisions. This selective rearrangement in Ru-MnCrO with particular spin-differentiated polarizations can induce localized spin domain inversion from reversed to parallel direction, which makes Ru-MnCrO demonstrate a high current density of 1.
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