arXiv subjects

S. Xia

Publications and source records attributed to S. Xia.

4 recordsLinked to original sources

arXiv2026

Enhanced magneto-optical intensity effect in a helicity-preserving all-dielectric metasurface at Mie resonances and the anapole state

Nanophotonic structures provide an efficient route to enhancing magneto-optical effects by concentrating electromagnetic fields at subwavelength scales. In this work, we propose and experimentally demonstrate a helicity-preserving all-dielectric metasurface for enhancing magnetization-induced transmission modulation under circularly polarized excitation. The optical response of the structure is governed by the Mie resonances of silicon nanodisks and by a spectral feature associated with the anapole state. In the spectral regions of the Mie resonances, the metasurface exhibits a pronounced enhancement of the magneto-optical intensity response relative to a bare magnetic film of the same thickness, with the normalized magneto-optical intensity effect increased by a factor of about 2-3. A strong response is also observed in the spectral region associated with the anapole state, manifested as a local transmission maximum. In this regime, the normalized magneto-optical intensity effect exceeds that of the bare magnetic film by about 30%, while the metasurface transmission remains as high as around 80%. The enhanced response in this spectral region is preserved over a broad range of incidence angles. These results demonstrate that all-dielectric metasurfaces combining Mie resonances with the spectral feature associated with the anapole state provide an efficient platform for magneto-optical intensity modulation of circularly polarized light at high transmission.

physics.optics↗

arXiv2025

Thermally-controlled magnetooptical metasurface for tunable Faraday rotation

We present novel type of tunable magneto-optical metasurfaces performing Faraday rotation, the sign and value of which are not fixed after the structure fabrication but can be tuned in a wide range via heating of the metasurface. We demonstrate both experimentally and theoretically that the Faraday rotation angle is enhanced in the vicinity of the magnetodipole and electrodipole Mie resonances and can be changed in a wide range from -0.3 degrees to +0.1 degrees for the same metasurface at fixed wavelength of incident light under the temperature changes from the 294~K to 488~K. Such thermal heating can be performed by an external control laser. As laser radiation can be focused at the spots of $~\sim 1\mu$m diameter, the magneto-optical response can also be tuned locally. Thus one may obtain the inhomogeneous magnetooptically-induced polarization rotation distributions across the metasurface by the creation of the laser beam patterns with the desired intensity profiles. Another possibility opened by the proposed merasurface is self-modulation of polarization of laser light performed depending on its intensity.

physics.optics↗

arXiv2022

Robustness versus sensitivity in non-Hermitian topological lattices probed by pseudospectra

Non-Hermitian topological systems simultaneously posses two antagonistic features: ultra sensitivity due to exceptional points and robustness of topological zero energy modes, and it is unclear which one prevails under different perturbations. We study that question by applying the pseudospectra theory on the prototypical non-Hermitian SSH (NHSSH) lattice. Topological modes are robust with respect to chiral perturbations and sensitive to parity-time (PT) symmetry preserving perturbations. In fact, the chiral symmetry exactly at the exceptional point leads to the suppression of its sensitivity, corresponding to a lower order exceptional point. However, counterintuitively, they are most sensitive with respect to unstructured perturbations, leaving the fingerprint of the pertinent higher order exceptional (HEP) point.

physics.optics↗

arXiv2010

Extraction of crystal-field parameters for lanthanide ions from quantum-chemical calculations

A simple method for constructing effective Hamiltonians for the 4fN and 4fN-15d energy levels of lanthanide ions in crystals from quantum-chemical calculations is presented. The method is demonstrated by deriving crystal-field and spin-orbit parameters for Ce3+ ions doped in LiYF4, Cs2NaYCl6, CaF2, KY3F10 and YAG host crystals from quantum chemical calculations based on the DV-Xα method. Good agreement between calculated and fitted values of the crystal-field parameters is obtained. The method can be used to calculate parameters even for low-symmetry sites where there are more parameters than energy levels.

cond-mat.mtrl-sci↗