Metasurfaces able to concentrate light at various wavelengths are promising for enhancing nonlinear interactions. In this Letter, we experimentally demonstrate infrared second-harmonic generation (SHG) by a multi-resonant nanostructure. A 100 GaAs layer embedded in a metal-insulator-metal waveguide is shown to support various localized resonances. One resonance enhances the nonlinear polarization due to the transverse magnetic (TM)-polarized pump wavelength near 3.2µ, while another is set near the TE-polarized generated wavelength (1.6µ). The measured SHG efficiency is higher than 10 for pump wavelengths ranging from 2.9 to 3.3µ, which agrees with theoretical computations. This is typically 4 orders of magnitude higher than the equivalent GaAs membrane.
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http://dx.doi.org/10.1364/OL.415257 | DOI Listing |
J Am Chem Soc
December 2024
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
The nonlinear optical response in graphene is finding increasing applications in nanophotonic devices. The activation and enhancement of second harmonic generation (SHG) in graphene, which is generally forbidden in monolayer and AB-stacked bilayer graphene due to their centrosymmetry, is of urgent need for nanophotonic applications. Here, we present a comprehensive study of SHG performance of twisted multilayer graphene structures based on stacking engineering.
View Article and Find Full Text PDFJ Am Acad Orthop Surg
December 2024
From the Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT (Graesser), the Washington University School of Medicine in St. Louis, Mallinckrodt Institute of Radiology, St. Louis, MO (Parsons), and the Department of Orthopaedic Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO (Olafsen, Dy, and Brogan).
Traumatic peripheral nerve injuries represent a spectrum of conditions and remain challenging to diagnose and prognosticate. High-resolution ultrasonography and magnetic resonance neurography have emerged as useful diagnostic modalities in the evaluation of traumatic peripheral nerve and brachial plexus injuries. Ultrasonography is noninvasive, is able to rapidly interrogate large areas and multiple nerves, allows for a dynamic assessment of nerves and their surrounding anatomy, and is cost-effective.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Departments of Physics, Chemistry, and Earth and Environmental Sciences, University of Illinois Chicago, Chicago, Illinois 60607, USA.
We study ferroelectricity in the classic perovskite ferroelectric PbTiO_{3} to high pressures with density functional theory (DFT) and experimental diamond-anvil techniques. We use second harmonic generation spectroscopy to detect lack of inversion symmetry. Consistent with early understanding and experiments, we find that ferroelectricity disappears at moderate pressures.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
Nonlinear optics plays important roles in the research of fundamental physics and the applications of high-performance optoelectronic devices. The bulk nonlinear optical responses arise from the uniform light absorption in noncentrosymmetric crystals, and hence are usually considered to be the collective phenomena of all atoms. Here we show, in contrast to this common expectation, the nonlinear optical responses in antiferromagnets can be selectively accumulated near the surfaces, representing a skin effect.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Nankai University, School of Materials Science and Engineering, CHINA.
Chiral hybrid organic-inorganic metal halides (HOMHs) hold great promise in broad applications ranging from ferroelectrics, spintronics to nonlinear optics, owing to their broken inversion symmetry and tunable chiroptoelectronic properties. Typically, chiral HOMHs are constructed by chiral organic cations and metal anion polyhedra, with the latter regarded as optoelectronic active units. However, the primary design approaches are largely constrained to regulation of general components within structural formula.
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