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Magneto-optical properties of asymmetric one-dimensional magneto-photonic crystals
摘要： We analytically investigate the magneto-optical properties of asymmetric one-dimensional magneto-photonic crystals (MPCs) by using our previously presented coupled mode description. We show that an MPC with one magnetic defect, placed asymmetrically, provides the same number of degrees of freedom as a symmetric double-defect MPC. Consequently, an asymmetric single-defect MPC allows arbitrary transmittance and Faraday rotation at the central frequency, just as a symmetric double-defect MPC, and hence a desired performance can be obtained by the more compact single-defect structure. However, the possible ranges of performance are more restricted than the possible ranges of a double-defect MPC. We present the synthesis relations to design the single-defect MPC. In a similar manner, we show that an asymmetric double-defect MPC provides more degrees of freedom than either a symmetric double-defect or an asymmetric single-defect MPC. The excessive degree allows us to design a more compact MPC than the symmetric double-defect MPCs for a desirable central frequency performance, in the wide possible range that double-defect structures provide.
关键词： Faraday rotation,Synthesis,Magneto-photonic crystals,Coupled mode theory
更新于2025-09-09 09:28:46
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Electric-field modulation of linear dichroism and Faraday rotation in few-layer phosphorene
摘要： Electro-optical modulators, which use an electric voltage (or an electric field) to modulate a beam of light, are essential elements in present-day telecommunication devices. Using a self-consistent tight-binding approach combined with the standard Kubo formula, we show that the optical conductivity and the linear dichroism of few-layer phosphorene can be modulated by a perpendicular electric field. We find that the field-induced charge screening plays a significant role in modulating the optical conductivity and the linear dichroism. Distinct absorption peaks are induced in the conductivity spectrum due to the strong quantum confinement along the out-of-plane direction and to the field-induced forbidden-to-allowed transitions. The field modulation of the linear dichroism becomes more pronounced with increasing number of phosphorene layers. We also show that the Faraday rotation is present in few-layer phosphorene even in the absence of an external magnetic field. This optical Hall effect is induced by the reduced lattice symmetry of few-layer phosphorene. The Faraday rotation is greatly influenced by the field-induced charge screening and is strongly dependent on the strength of perpendicular electric field and on the number of phosphorene layers.
关键词： electric field modulation,linear dichroism,optical conductivity,Faraday rotation,electro-optical modulators,few-layer phosphorene
更新于2025-09-09 09:28:46
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The structure, spectra and properties of Dy2O3 modified diamagentic lead-bismuth-germanium glasses
摘要： Dy2O3 is potential and attractive as scintillator, mid infrared laser and Faraday rotation materials in high energy physics, general radiation and magneto optical sensing systems. In this study, Dy3+ doped diamagnetic glasses with compositions of 10GeO2 – 30PbO – 50Bi2O3 – (10-x)B2O3 –xDy2O3 (x = 0, 0.5, 1, 2, 3, 5 M %) were fabricated by a melt quenching technique. The modification of Dy3+on glass forming, structure, UV–Vis, FT-IR, Raman and photoluminescence spectra and properties were investigated through XRD, Raman spectra, DSC, Vicker's hardness and Verdet constant measurements etc. Melt with Dy2O3 content beyond 5% prefer to crystallize, not to form glassy matrix. The UV visible absorption spectra showed three intense bands at 483 nm, 575 nm and 661 nm due to 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow) and 4F9/2 → 6H11/2 (red) transitions, respectively. Judd-Ofelt paramaters have been calculated to verify network connectivity of Dy2O3 doped glasses. FT-IR and Raman spectrum depicted the presence of PbO4, BiO3, GeO6, BO3 frame groups and DyeO bonds from cubit Dy2O3. Glass doped with 1%Dy2O3 exhibited promising thermal stability (97 °C), microhardness (480 HV) and magneto-optical activity (0.1864 min/G.cm@532 nm) due to the high optical dispersion, high ion polarizability of Dy3+ ions
关键词： Heavy metal oxide glass,Faraday rotation,Dy2O3,Diamagnetic glass
更新于2025-09-04 15:30:14
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An upgraded interferometer-polarimeter system for broadband fluctuation measurements
摘要： Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°–0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibrium and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.
关键词： Faraday rotation,interferometer-polarimeter,planar-diode mixer,broadband fluctuation measurements,phase noise
更新于2025-09-04 15:30:14