Mirror symmetries are of particular importance because they are connected to fundamental properties and conservation laws. Spatial inversion and time reversal are typically associated to charge and spin phenomena, respectively. When both are broken, magnetoelectric cross-coupling can arise. In the optical regime, a difference between forward and backward propagation of light may result. Usually, this nonreciprocal response is small. We show that a giant nonreciprocal optical response can occur when transferring from linear to nonlinear optics, specifically second harmonic generation (SHG). CuBO exhibits SHG transmission changes by almost 100% upon reversal of a magnetic field of just ±10 mT. The observed nonreciprocity results from an interference between magnetic-dipole and electric-dipole SHG. Although the former is inherently weaker than the latter, a resonantly enhanced magnetic-dipole transition has a comparable amplitude as a nonresonant electric-dipole transition, thus maximizing the nonreciprocity. Multiferroics and magnetoelectrics are an obvious materials platform to exhibit nonreciprocal nonlinear optical functionalities.
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http://dx.doi.org/10.1126/sciadv.abe2793 | 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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