We report a detailed investigation on the second harmonic generation (SHG) emission from single 150 nm diameter non-centrosymmetric gold nanoparticles. Polarization-resolved analysis together with scanning electron microscopy images shows that these nanostructures exhibit a unique polarization-sensitive SHG that depends strongly on the particle's shape. An analytical approach based on multipolar analysis is introduced to link SHG properties to the nanoparticles' shape. Those multipolar modes can be probed using polarization-resolved SHG. This multipolar analysis offers a physical picture of the relation between shape (size, symmetries, defects, etc.) and nonlinear polarized optical efficiency.
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http://dx.doi.org/10.1364/OE.27.005620 | DOI Listing |
PLoS One
January 2025
Department of Epidemiology and Biostatistics, School of Public Health, University at Albany, State University of New York, Rensselaer, New York, United States of America.
Since the emergence of the SARS-CoV-2 virus, research into the existence, extent, and pattern of seasonality has been of the highest importance for public health preparation. This study uses a novel bandpass bootstrap approach called the Variable Bandpass Periodic Block Bootstrap to investigate the periodically correlated components including seasonality within US COVID-19 mortality. Bootstrapping to produce confidence intervals for periodic characteristics such as the seasonal mean requires preservation of the periodically correlated component's correlation structure during resampling.
View Article and Find Full Text PDFChem Sci
January 2025
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China
Traditional tetrahedral-based mid-to-far infrared (MFIR) nonlinear optical (NLO) crystals often face limitations due to the optical anisotropy constraints imposed by their highly symmetric structures. In contrast, the relatively rare trigonal pyramidal [TeS] functional unit characterized by its asymmetric structure and stereochemically active lone pair (SCALP), offers improved optical anisotropy, hyperpolarizability and a broader IR transparency range. Despite its potential, synthetic challenges have hindered the development of MFIR NLO crystals that incorporate this unit, with only one example reported to date.
View Article and Find Full Text PDFFront Bioeng Biotechnol
January 2025
Department of Biomedical Engineering, The City College of New York, New York, NY, United States.
Many biological fibrous tissues exhibit distinctive mechanical properties arising from their highly organized fibrous structure. In disease conditions, alterations in the primary components of these fibers, such as type I collagen molecules in bone, tendons, and ligaments, assembly into a disorganized fibers architecture generating a weak and/or brittle material. Being able to quantitatively assess the fibers orientation and organization in biological tissue may help improve our understanding of their contribution to the tissue and organ mechanical integrity, and assess disease progress and therapy effect.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Physics, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, China.
Two-dimensional (2D) materials with spontaneous polarization can exhibit large second-order nonlinear optical (NLO) effects. Here, we present a series of stable distorted monolayers by using first-principles calculations and lattice vibration analysis. The structural distortion leads to a lower polar symmetry, giving rise to intrinsic ferroelectricity with a Curie point up to room temperature.
View Article and Find Full Text PDFNano Lett
January 2025
School of Physics and Technology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China.
Hybrid nonlinear plasmonic waveguides, characterized by a small mode area and large nonlinear susceptibility, present an intriguing and practical platform for the minimization of nonlinear photonic devices. Nevertheless, the intrinsic Ohmic loss associated with surface plasmon polaritons (SPPs) and modal dispersion imposes constraints on the effective interaction length and, consequently, the ultimate efficiency of nonlinear processes. In this study, we demonstrate an efficient second harmonic generation (SHG) within a hybrid plasmonic waveguide by leveraging SPP-like modes at the fundamental wave and photonic-like modes at the SHG under phase matching conditions.
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