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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5365-5365 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nonlinear waves in the form of solitons in magnetic films are attracting attention because of the interesting possibility of making novel spatial, and temporal, soliton devices that will operate in the technologically important microwave (GHz) frequency window. Some fascinating pioneering experimental work has been performed in this area and there is now every possibility that manipulation of solitonlike microwave pulses will be the basis of an entirely new range of devices. Both theory and experiment show that solitons are extremely robust and behave rather like particles. Magnetic films look set to become as successful as optical fibers in supporting bright envelope solitons; yet soliton behavior can often seem hard to comprehend. While they are subtle in their behavior they can be understood from many points of view that are physically, or mathematically, based. This presentation will explain what bright microwave envelope solitons are, drawing upon as much physical insight and analogy as possible. The necessary and sufficient conditions for soliton existence will be carefully set out, especially with respect to their relationship to the input conditions of a device. A substantial number of numerical examples will be used and the prospects for major expansion in the experimental area will be assessed. In the latter part of the presentation some important applications for solitons will be addressed. These will include the analysis of a switching device but logic devices, and various forms of pump–probe arrangements, will also be retrieved. Finally, the optimistic view that solitons in magnetic materials are now realistic tools will be expressed and the opportunities provided by dark and higher-dimensional solitons will be discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: TE/TM polarized light reflection from a multilayer structure containing a magneto-optic (MO) and a metal film is investigated theoretically and experimentally. A metal film is used whose thickness is chosen to support long-range surface polaritons (SP). This is to use their sharp resonance for tuning the whole structure. It was shown that if the MO layer is placed in a multilayer structure consisting of a thin metal film that supports a long-range surface polariton, the resonance couples to the off-diagonal element of the YIG-film dielectric tensor. This means that this process exhibits a nonreciprocal property, as well as a Faraday rotation in the MO film. A combination of these two effects enhances the value of the magneto-optic quality (Faraday rotation divided by the losses incurred by the light) and the nonreciprocity of the light reflection from the structure. Theoretical and experimental optimization of these effects at a wavelength equal to 0.5 μm has been carried out for thin monodomain single crystal YIG films, saturated by a magnetic field of the order 1 Oe. It has enabled the design of a high frequency operation circulator to be developed. These results will be reported in this paper.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low power magnetostatic wave (MSW) experiments reporting beam formation and propagation inside ferromagnetic films have been carried out .1,2 In this work, we report the first observation of self channeling of MSW and the formation of the spatial solitons of MSW for an in-plane magnetized YIG film and waves propagating perpendicularly to the direction of magnetization. The experiments were conducted using YIG film of 4.9 μm thickness magnetized in-plane by a permanent magnetic field of 1094 Oe. A cw signal was launched into the film through a microstrip antenna. A Brillouin scattering system consisting of a tandem Fabry–Perot interferometer has been used to observe the profile of a MSW beam. Self-channeling MSW beam propagation occurring as a result of an interplay between diffraction of the beam and self-modulation was observed for various magnitudes of input power and initial frequency. At low power levels the formed MSW beam broadens and weakens during the propagation. As the input power increases, the intensity of the peak power of the beam also increases and a narrow channel of the MSW beam is formed. The power threshold depends on the wavelength of MSW and the width of the excitation microstrip. A theory describing the spatial MSW self-channeling is developed. The necessary and sufficient conditions are analyzed and numerical calculations are provided. The experimental data are in a semi-quantitative agreement with theory.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5631-5631 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The propagation of nonlinear dipole spin waves in a film consisting of a two sublattice, uniaxial, antiferromagnetic material has been investigated. The system when the external magnetic field is assumed to be parallel to the anisotropy axis of the antiferromagnetic film and is directed parallel, or perpendicular, to the film surface is considered. For the first case, surface and volume waves can propagate in the film, and for the second case, volume waves can propagate in the film for a rather weak external magnetic field when the magnetization of the sublattices are counter parallel to each other and are perpendicular to the film surface. The linear dispersion relations for all three types of waves are analyzed and their group velocity dispersion is calculated. The nonlinear shift of the frequency, due to the finite power of the wave, is also obtained for the three types of dipole waves for the case of a thin antiferromagnetic film, when kd(very-much-less-than)1 (k is the wave number and d is the thickness of the film). The nonlinear Schrödinger equation governing the propagation of the nonlinear spin wave in the film is investigated. It is shown that the criterion for the existence of spin wave solitons is fulfilled, for parallel magnetization, which permits the existence of surface waves (one branch) and volume waves (both branches), but the criterion is not fulfilled for perpendicular magnetization. The power threshold for soliton creation is also calculated and estimates are given for the data appropriate to a MnF2 crystal.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 41-47 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A phase fluorometer based on a low-cost and versatile high-frequency modulated light source and a fast gain-modulated photomultiplier is described. The apparatus is particularly well-suited to high-sensitivity frequency-domain fluorescence measurements requiring ultraviolet excitation. The system is very compact since it features a directly modulated light source, a miniature photomultiplier tube, and an rf synthesizer on a PC board. Equipped with a suitable fiber optic probe sensor, the device has potential as a portable unit for a wide range of remote sensing applications. The lamp can be modulated at frequencies up to 120 MHz and the phase fluorometer has been tested at up to 70 MHz with a range of fluorescent lifetime standards containing quinine sulfate quenched with sodium chloride. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 4453-4456 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spin-wave excitations have been observed, using Brillouin light scattering, in thin films of TbFeCo, grown by sputtering on silicon substrates, with thicknesses in the range 4.5–250 nm. The variations of spin-wave frequency with applied in-plane magnetic-field H (100 Oe≤H≤4.5 kOe) and in-plane magnon wave-number k (4.24×104≤k≤2.41×105 cm−1) were obtained. For these films, oxidation during the deposition process produces a bulk film, which is very weakly ferrimagnetic and, therefore, largely magnetically dead. However, further oxidation, at the film surface after deposition, due to exposure to air, increases the magnetization to produce a magnetically active surface layer. The results were modeled as a Damon–Eshbach surface mode, and the TbFeCo films considered as a magnetic film on a nonmagnetic layer, the thicknesses of which were both unknown. The frequency versus field measurements enabled values for the saturation magnetization and gyromagnetic ratio to be determined. The measurements of the frequency versus wave number showed evidence that, for the thicker films, the magnetically active layer was only a small fraction of the total thickness, and the active layer thicknesses were determined. The values of magnetizations are compared with those obtained from vibrating sample magnetometry measurements. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 266-268 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Energy switching is investigated, both theoretically and experimentally, between two identical ferromagnetic films. The frequency region, and the applied magnetic field direction selected, permits a magnetostatic surface wave to be generated in each film. After the exact theory for this magnetostatic directional coupler is given, an experimental study of the evolution of the magnetic field distribution is presented. Good agreement between theory and experiment is obtained. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1940-1942 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that nonlinear mode coupling in a double-antiresonant reflecting optical waveguide structure leads to the power-dependent switching of an optical signal between remote channels.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 30 (1998), S. 891-905 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The four vector equations, appropriate to a mixed type I–type II second-harmonic generation, in a thin planar waveguide, made from a second-order non-linear material, are solved, both approximately and exactly. The solutions are then used to generate possible applications. In this investigation, both the fundamental and the second-harmonic waves have two transverse field components. It is shown that, by controlling the ratio of the components of the fundamental wave, one component of the second-harmonic wave can be rigorously controlled, and even switched off. The ratio of the harmonic field components depends strongly upon the polarization angle of the fundamental wave, with the extinction angle depending strongly upon the phase mismatch parameter. In a second application, an aperture is placed at the output and it is shown that if approximate stationary states are used as an input to a quadratically non-linear medium, then varying the angle of incidence of two input beams produces an excellent output control. A numerical demonstration is given in which a switch from 80% of the input energy arriving at the output port to less than 3% is readily achievable.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 26 (1994), S. S321 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstact This paper focuses upon the kind of tapered waveguide structure that could be used, in integrated optics, for mode size control in two dimensions. The stationary states for various values of rib width, and rib height, are calculated for the case when a smaller rib sits upon a much wider one. A finite element package has been developed to effect the analysis and this is complemented with a three-dimensional beam propagation program. Modal control is demonstrated as the tapering proceeds. Finally, self-defocusing nonlinearity in introduced, with the ability of the power level to spread the field out from under the small rib into the lower (wider) ribbed guide being illustrated numerically.
    Type of Medium: Electronic Resource
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