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Additional Nonreciprocity Effects in the Magneto-Optics of Asymmetric Layer Structures
摘要： It has been shown that space–time inversion symmetry breaking at the normal incidence of a quasiplane wave on an asymmetric multilayer structure in the Voigt geometry can result in the formation of the angular Goos–H?nchen effect at reflection and transmission, as well as the spatial Goos–H?nchen effect at transmission. The effects are characterized by nonreciprocity not only with respect to the inversion of direction of static magnetic field but also with respect to the permutation of nongyrotropic layers surrounding a gyrotropic layer.
关键词： asymmetric layer structures,nonreciprocity,Voigt geometry,magneto-optics,Goos–H?nchen effect
更新于2025-09-23 15:22:29
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Tailoring coupling between light and spin waves with dual photonic-magnonic resonant layered structures
摘要： We report on judiciously designed stratified periodic structures of magnetic dielectric materials with a localized defect layer, which are able to concurrently confine light and spin waves in the same ultra-small defect region for a long time period, thus resulting in enhanced photon-magnon interaction and large dynamic optical frequency shift. Our results for a specific realization of such a one-dimensional, so-called photomagnonic, crystal magnetized at saturation perpendicular to the interfaces, obtained by means of rigorous calculations using scattering-matrix techniques, show that the inherently weak coupling between visible/near-infrared light and GHz-frequency spin waves can be greatly increased leading to strong modulation of the optical field through multi-magnon exchange mechanisms. Such novel multifunctional composite materials offer a promising platform for tailoring light–spin-wave coupling in view of fast and energy-efficient spin-optical information processing applications.
关键词： Inelastic Light Scattering,Photomagnonic Crystal,Magneto-optics,Spin Waves
更新于2025-09-23 15:21:01
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Characterisation of spectroscopic and magneto-optical faraday rotation in Mn2+- doped CdS quantum dots in a silicate glass
摘要： We demonstrate the control of CdS and Mn2+-doped-CdS Q-dots in a silicate glass for magneto-optical applications. The microstructural properties of Q-dot glasses were investigated by X-Ray diffraction (XRD), Field Emission Transmission Electron Microscopy (FETEM) and the optical properties by UV-Visible-NIR and Photoluminescence (PL) spectroscopic techniques, respectively. The FETEM of the CdS QD–glass heat treated at 600oC reveals that the size of CdS and Mn2+-doped CdS Q-dots are in the range of 4-5 nm and 5-6nm, respectively. The observed size distributions of Q-dots were in reasonable agreement with the data, derived from X-ray line broadening and estimated average Bohr radii using the UV-visible absorption data. Photoluminescence characteristics were investigated at room temperature by exciting the CdS and Mn2+-doped-CdS Q-dot glasses with a 420 nm excitation source, which yielded broad emission spectra in the visible and near-IR range (450-800nm). We observed a red shift in the emission peak with increase in the Q-dot size, controlled by heat treatment temperature range (550-600oC). The room-temperature magneto-optical Faraday rotation measurements on Q-dots glasses were carried out using magnetic field strength up to 360 mT, and observed an increase in the value of Verdet constant, from 6.2 to 12.0 degree/T-cm, when comparing undoped CdS-Q-dot glass with Mn2+-doped CdS glass. The demonstration of enhanced Verdet constant in Q-dot silicate glasses with sub-Tesla field paves the path for engineering range magneto-optical devices for photonics, spintronics and sensors applications, in which the polarisation of photons may be controlled with low-intensity magnetic field in optical waveguides.
关键词： Faraday rotation,Quantum dots CdS,Photoluminescence,Dichalcogenide glass,Magneto-optics
更新于2025-09-19 17:13:59
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Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
摘要： Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by local enhancement of electric field intensity that strengthens light-matter interactions, enabling applications such as surface-enhanced Raman scattering (SERS) and surface plasmon enhanced sensing. In the presence of magneto-optically active materials, the local field enhancement gives rise to anomalous magneto-optical activity. Typically, the confined modes of a given photonic crystal depend strongly on the wavelength and incidence angle of the incident electromagnetic radiation. Thus, spectral and angular-resolved measurements are needed to fully identify them as well as to establish their relationship with the magneto-optical activity of the crystal. In this article, we describe how to use a Fourier-plane (back focal plane) microscope to characterize magneto-optically active samples. As a model system, here we use a plasmonic grating built out of magneto-optically active Au/Co/Au multilayer. In the experiments, we apply a magnetic field on the grating in situ and measure its reciprocal space response, obtaining the magneto-optical response of the grating over a range of wavelengths and incident angles. This information enables us to build a complete map of the plasmonic band structure of the grating and the angle and wavelength dependent magneto-optical activity. These two images allow us to pinpoint the effect that the plasmon resonances have on the magneto-optical response of the grating. The relatively small magnitude of magneto-optical effects requires a careful treatment of the acquired optical signals. To this end, an image processing protocol for obtaining magneto-optical response from the acquired raw data is laid out.
关键词： plasmonics,magneto-optics,magnetoplasmonics,photonic crystals,Issue 153,Engineering,spectroscopy,back focal plane measurement
更新于2025-09-11 14:15:04
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Optical signatures of Dirac nodal lines in NbAs <sub/>2</sub>
摘要： Using polarized optical and magneto-optical spectroscopy, we have demonstrated universal aspects of electrodynamics associated with Dirac nodal lines that are found in several classes of unconventional intermetallic compounds. We investigated anisotropic electrodynamics of NbAs2 where the spin-orbit coupling (SOC) triggers energy gaps along the nodal lines. These gaps manifest as sharp steps in the optical conductivity spectra σ1(ω). This behavior is followed by the linear power-law scaling of σ1(ω) at higher frequencies, consistent with our theoretical analysis for dispersive Dirac nodal lines. Magneto-optics data affirm the dominant role of nodal lines in the electrodynamics of NbAs2.
关键词： Dirac fermions,nodal-line semimetal,optical conductivity,magneto-optics
更新于2025-09-09 09:28:46