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1

Digitale Medien

Magneto-optic waveguide hysteresis loops of "planar'' magnetic garnet films (1989)

McGlashan-Powell, M. ; Wolfe, R. ; Dillon, J. F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 66 (1989), S. 3342-3347

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Epitaxial films of modified yttrium iron garnet which are used as optical waveguides for magneto-optic devices have nominally planar anisotropy so that their magnetization can be aligned by small in-plane fields. Films grown on (111) substrates usually have some residual cubic anisotropy that is difficult to measure in the active layer of the double- or triple-layer films used in single-mode waveguides. A new method to determine the magnetic properties of the optically active layer itself has been developed. It is based on magneto-optical hysteresis loops in which the Faraday rotation of the waveguided light is plotted against one component of a rotating in-plane magnetic field. Steps in these hysteresis loops are directly related to the sixfold symmetry of the magnetocrystalline anisotropy of these films. The influence of linear birefringence on the measured Faraday rotation, the magnetostrictive effects associated with the pressure of the prism used for optical coupling into the waveguide, and the advantages of end-fire coupling are discussed. These hysteresis loops are being used in the design of materials for magneto-optic isolators and other waveguide devices.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.344131

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2

Digitale Medien

Polar Kerr effect in high-Tc superconductors: The rotating-plate technique (1991)

Lyons, K. B. ; Dillon, J. F. ; McGlashan-Powell, M.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 70 (1991), S. 1060-1062

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: A technique recently used for measurement of the complex polar Kerr rotation in high-Tc superconductors is discussed in a tutorial manner, making use of a Jones matrix approach. The primary concern addressed is the rejection of effects caused by linear birefringence and dichroism effects in the sample and associated optical components. This rejection is accomplished by the use of a rotating half-wave retardation plate.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.349696

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3

Digitale Medien

The search for circular dichroism in high-Tc superconductors (abstract) : 35th annual conference on magnetism and magnetic materials (1991)

Lyons, K. B. ; Kwo, J. ; Dillon, J. F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 69 (1991), S. 5205-5205

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Stimulated by recent predictions of broken time reversal symmetry in cuprate superconductors, we have carried out a study of the polar Kerr ellipticity (the ellipticity of normally reflected light with the incident beam linearly polarized) for various cuprate materials, both superconducting and nonsuperconducting. The technique used employs a rotating half-wave retardation plate in order to discriminate against linear polarization effects. The results reveal a signature of a nonzero polar Kerr ellipticity which appears on cooling near 200 K in a variety of superconducting materials, and which is not observed in the corresponding insulating compounds. In this talk, in addition to summarizing these results, we plan to discuss the measurement technique itself in some detail. Measurements on both thin films and bulk samples will be discussed, together with a variety of tests on unrelated materials, which serve to eliminate various possible experimental artifacts.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.348075

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4

Digitale Medien

Thin-film garnet materials with zero linear birefringence for magneto-optic waveguide devices (invited) (1988)

Wolfe, R. ; Fratello, V. J. ; McGlashan-Powell, M.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 63 (1988), S. 3099-3103

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The many advantages of thin-film waveguide magneto-optic devices have been difficult to realize because of the linear birefringence of these films, which makes it very difficult to achieve the required Faraday rotation. In epitaxial garnet films, this linear birefringence (the difference between the refractive indices of the TE and TM modes) can be reduced to small values by (1) growing single-mode multilayer films to minimize the shape effect, (2) growing the films in compression to control the photoelastic effect, and (3) annealing at high temperatures to eliminate the growth-induced effect. The remaining birefringence can be reduced to zero by growing the top active layer too thick so that the shape effect is smaller in magnitude than the stress effect, and then thinning it by chemical etching until the effects exactly cancel each other at a particular wavelength. An alternative method is to grow the top layer too thin and then to deposit a dielectric layer such as silicon nitride of the proper thickness to reduce the shape effect so that it exactly cancels the stress effect. Theoretical results on multilayer magneto-optic waveguides and successful etch-tuning experiments at 1.32 and 1.51 μm are presented. These tuning procedures can produce polarization-independent waveguide devices such as isolators or polarization rotators which may replace bulk or thick-film devices.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.340881

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5

Digitale Medien

Elimination of birefringence in garnet films for magneto-optic waveguide devices (1987)

Wolfe, R. ; Fratello, V. J. ; McGlashan-Powell, M.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 51 (1987), S. 1221-1223

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The linear birefringence of magneto-optic garnet thin films, which interferes with the Faraday rotation in waveguide devices, can be reduced to small values by growing multilayer films to minimize the shape effect, annealing at high temperatures to reduce the growth-induced effect, and growing the films in compression to control the photoelastic effect. The remaining birefringence can be reduced to zero by chemically etching the film until the effects exactly cancel each other at a particular wavelength. This etch-tuning procedure is demonstrated on a two-layer bismuth-yttrium iron garnet (Bi-YIG) film at wavelengths of 1.51 and 1.32 μm. Extinction ratios of 100 to 1 have been achieved at 45° and 90° Faraday rotations at both wavelengths.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.98736

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6

Digitale Medien

Thin metal foil vacuum interface for low energy particle accelerators

McGlashan-Powell, M.

Amsterdam : Elsevier

Nuclear Instruments and Methods 177 (1980), S. 317-320

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ISSN: 0029-554X

Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Thema: Energietechnik , Physik

Materialart: Digitale Medien

URL: http://linkinghub.elsevier.com/retrieve/pii/0029-554X(80)90039-7

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