For the permittivity tensor of photoelastic anisotropic crystals, we obtain the exact nonlinear dependence on the Cauchy stress tensor. We obtain the same result for its square root, whose principal components, the crystal principal refractive index, are the starting point for any photoelastic analysis of transparent crystals. From these exact results we then obtain, in a totally general manner, the linearized expressions to within higher-order terms in the stress tensor for both the permittivity tensor and its square root. We finish by showing some relevant examples of both nonlinear and linearized relations for optically isotropic, uniaxial and biaxial crystals.
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http://dx.doi.org/10.1098/rspa.2019.0854 | DOI Listing |
Materials (Basel)
December 2024
Institute for Pulsed Power and Microwave Technology IHM, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Estimating the effective permittivity of anisotropic fibrous media is critical for advancing electromagnetic applications, requiring detailed microstructural and orientation analyses. This study introduces innovative approaches for disclosing the orientation and microstructure of fibers, leading to mixing relations. It particularly focuses on two specific fiber configurations: 1.
View Article and Find Full Text PDFActa Crystallogr B Struct Sci Cryst Eng Mater
December 2024
Department of Materials Science and Engineering, Clemson University, Clemson, SC 29634, USA.
Averaging of material coefficients of crystallites deposited at an angle to a rotating substrate is considered. A simple model is proposed, and applied to determine effective linear dielectric, piezoelectric, and elastic constants of all Laue groups. While these represent tensors of rank 2, 3, and 4, the method applies generally to tensors of any rank.
View Article and Find Full Text PDFWe realized fourth-order exceptional points (EP-4s) in the quasienergy bands of anisotropic photonic time-Floquet crystals (APTCs), where the full in-plane permittivity tensors are periodically modulated in time. We developed the Floquet matrix method for APTCs, which provides a comprehensive study of the generation and characteristics of EP-4s. It is shown that an EP-4 is formed by the coalescence of three second-order exceptional points (EP-2s), which are classified into two types based on the band slopes near them.
View Article and Find Full Text PDFPhys Rev E
August 2024
Department of Physics, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Bilbao, Spain.
Ferroelectric nematic liquid crystals are currently being subject to a plethora of investigations since they are of great fundamental interest and could potentially foster promising applications. However, many basic aspects are still poorly understood, among which the problem of the dielectric constant stands out. Ferroelectric nematics have previously been reported to exhibit giant dielectric constants whose value depends on the thickness of the measurement cell, claims that have recently been shown to be the result of an incorrect interpretation of the experimental data.
View Article and Find Full Text PDFWe present a novel, to the best of our knowledge, magneto-optical (MO) metasurface composed of a bismuth iron garnet (BIG) nanocube array, designed to achieve near-perfect absorption through quasi-bound states in the continuum (QBICs). This metasurface supports a stable QBIC mode induced by MO-induced permittivity terms that break the symmetry of the permittivity tensors, corresponding to a longitudinal electric dipole (ED) mode. By integrating graphene to introduce material loss, the absorption reaches 99.
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