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Here we report on designing a magnetic field sensor based on magnetoplasmonic crystal made of noble and ferromagnetic metals deposited on one-dimensional subwavelength grating. The experimental data demonstrate resonant transverse magneto-optical Kerr effect (TMOKE) at a narrow spectral region of 50 nm corresponding to the surface plasmon-polaritons excitation and maximum modulation of the reflected light intensity of 4.5% in a modulating magnetic field with the magnitude of 16 Oe. Dependences of TMOKE on external alternating current (AC) and direct current (DC) magnetic field demonstrate that it is a possibility to use the magnetoplasmonic crystal as a high-sensitive sensing probe. The achieved sensitivity to DC magnetic field is up to 10−6 Oe at local area of 1 mm2.

We demonstrate a logic gate based on interference of forward volume spin waves (FVSWs) propagating in a 54 nm thick, 100 μm wide yttrium iron garnet waveguide grown epitaxially on a garnet substrate. Two FVSWs injected by coplanar waveguides were made to interfere constructively and destructively by varying their phase difference, showing an XNOR logic function. The reflected and resonant waves generated at the edges of the waveguide were suppressed using spin wave absorbers. The observed isolation ratio was 19 dB for a magnetic field of ~2.80 kOe ( = 223 kA m−1) applied perpendicular to the film. The wavelength and device length were ~8.9 μm and ~53 μm, respectively. Further, the interference state of the SWs was analyzed using three-dimensional radio frequency simulations.

A nonlinear spin-wave (magnonic) logic gate based on the ferrite-film Mach-Zehnder interferometer was realized. The gate has two inputs and one output. The principle of operation of the device is based on the power-dependent phase shift of spin waves propagating in an yttrium iron garnet film. A XOR logic functionality for two digital data streams supplied to the gate inputs is shown. No control signal is needed for the gate operation. The performance characteristics of the device are discussed. Reliable functionality in the pulsed regime at 50 and 250 kb/s is demonstrated.

Strong- and broadband-spin wave (SW) excitation/detection structures are useful for magnonic devices. In particular, such structures are essential for observing magnonic bandgaps of magnonic crystals (MCs). Therefore, this study proposes a manufacturable broadband-SW excitation/detection antenna structure suitable for evaluating MCs. The antenna structure comprises a microstrip line fabricated on a yttrium iron garnet on a metal-covered silicon substrate. Calculations were performed using a three-dimensional finite integration technique and dispersion curves of SWs. The proposed structure exhibited high performance because of the significantly short distance between the signal line and ground plane. The generated bandwidth was ∼1.69 GHz for the 8.9 μm-wavelength SW at a frequency of 4 GHz. This work proposed an appropriate antenna structure for observing magnonic bandgaps, showing high potential for the development of MCs in integrated SW devices.

Structural Magnetostrictive Alloys: From Flexible Sensors to Energy Harvesters and Magnetically Controlled Auxetics

In the fifty years since the postulation of Moore’s Law, the increasing energy consumption in silicon electronics has motivated research into emerging devices. An attractive research direction is processing information via the phase of spin waves within magnonic-logic circuits, which function without charge transport and the accompanying heat generation. The functional completeness of magnonic logic circuits based on the majority function was recently proved. However, the performance of such logic circuits was rather poor due to the difficulty of controlling spin waves in the input junction of the waveguides. Here, we show how Snell’s law describes the propagation of spin waves in the junction of a Ψ-shaped magnonic majority gate composed of yttrium iron garnet with a partially metallized surface. Based on the analysis, we propose a magnonic counterpart of a core-cladding waveguide to control the wave propagation in the junction. This study has therefore experimentally demonstrated a fundamental building block of a magnonic logic circuit.

Hologram memory is a strong candidate for optical storage due to its high recording density and high data transfer rate. We have studied and engineered a magnetic hologram memory medium using a stable magnetic garnet as recording material. To record a deep and clear magnetic hologram, it is important to control the heat diffusion generated during recording. Numerical simulation suggested that a multilayer structure with transparent heat-dissipation layers would be effective to address this. We fabricated a multilayer magnetic medium for a collinear magnetic hologram. This medium exhibited a diffraction efficiency as high as that of the single layered one, and errorless recording and reconstruction was achieved with the magnetic assist technique.

Magnetoplasmonic crystals consisted of a combination of noble and ferromagnetic thin films deposited on the diffraction gratings represent a special class of nanostructures that can utilize the magneto-optical Kerr effect enhanced by surface plasmon-polaritons excitation for the probing of an external DC magnetic field. Optical and magneto-optical properties of a magnetoplasmonic crystal are formed by magnetic behavior. This article represents the ways to manipulate the optical, magneto-optical and magnetic properties of nickel-based magnetoplasmonic crystals by the variation of the substrate parameters, the composition of magnetoplasmonic crystals as well as the compressive mechanical stresses on the surface of a ferromagnetic layer.

Magneto-optical (MO) effects enable non-reciprocal optical components like optical circulators and isolators as well as a magneto-optical spatial light modulator with switching speeds superior to a digital micromirror and a liquid crystal device. To develop a magneto-optical device with high performance, it is desirable to use materials with large rotation angles and small extinction coefficients. In other approaches introduction of nanostructures, magnetophotonic crystals [1] and localized surface plasmon resonance (LSPR) [2] has been shown to provide enhancement of the Faraday effect for distinct wavelengths. This work shows how rectangular arrays of gold (Au) particles embedded into thin films of bismuth-substituted yttrium iron garnet (Bi:YIG) offer different phenomena in comparison with the square arrays previously studied [3] [4] [5]. This enhancement of Faraday rotation was first observed in samples fabricated and characterized experimentally [6].

Planar magnetoplasmonic nanogratings composed of a two-dimensional square array of gold nanoparticles embedded into thin magnetic garnet films are proposed for enhancement of the transverse magneto-optical Kerr effect due to excitation of a quasi-waveguiding mode with light concentrated mostly inside the magnetic film. A proper optimisation of the size and periodicity of plasmonic nanoparticles as well as the thickness of magnetic dielectrics allows spectral tuning of the waveguiding mode leading to the sharp asymmetric resonance in the magneto-optical response in the desired spectral region.

Diode-pumped solid-state micro lasers are compact (centimetre-scale), highly stable, and efficient. Previously, we reported Q-switched lasers incorporating rare-earth substituted iron garnet (RIG) film. Here, the first demonstration of the magnetooptical (MO) Q-switch in an Nd:YAG laser cavity is performed. We fabricate a quasi-continuous-wave (QCW) diode-pumped Nd:YAG laser cavity, which is shortened to 10 mm in length and which contains an RIG film and a pair of small coils. This cavity yields a 1,064.58-nm-wavelength pulse with 25-ns duration and 1.1-kW peak power at a 1-kHz repetition ratio. Further, the polarisation state is random, due to the isotropic crystal structure of Nd:YAG and the fact that the MO Q-switch incorporating the RIG film does not require the presence of polarisers in the cavity. This is also the first report of an MO Q-switch producing random polarisation.

Thin film oxide materials often require thermal treatment at high temperature during their preparation, which can limit them from being integrated in a range of microelectronic or optical devices and applications. For instance, it has been a challenge to retain the optical properties of Bragg mirrors in optical systems at temperatures above 700 °C because of changes in the crystalline structure of the high–refractive-index component. In this study, a ~100 nm–thick amorphous film of tantalum oxide and yttrium oxide with an yttrium-to-tantalum atomic fraction of 14% was prepared by magnetron sputtering. The film demonstrated high resistance to annealing above 850 °C without degradation of its optical properties. The electronic and crystalline structures, stoichiometry, optical properties, and integration with magnetooptical materials are discussed. The film was incorporated into Bragg mirrors used with iron garnet microcavities, and it contributed to an order-of-magnitude enhancement of the magnetooptical figure of merit at near-infrared wavelengths.

Magnetic holographic memory is expected as a rewritable high-capacity data storage technology. To improve the reconstructed image, we investigate recording conditions by numerical simulation and experiments. We found experimentally that four diffracted beams from a digital micromirror device interfere with each other at a suitable defocus recording point, and such overlapping is favorable to obtain clear reconstruction images without diffuser. Subsequently, we modify the shape of the reference beam to ensure more effective interference. As a result, we achieve error-free image reconstruction from the magnetic hologram. Our results indicate that magnetic holograms can potentially be utilized as holographic memory.

Hologram memory is expected to be the next-generation of optical data storage technology. Bismuth-substituted yttrium iron garnet is typically used for rewritable magnetic hologram media. The diffraction efficiency of magnetic holography depends on the Faraday rotation angle, but the experimental diffraction efficiency is not as high as that expected from calculations. This difference could be caused by incomplete magnetization reversal at the recorded region. In this study, we investigated the effects of magnetic assist (MA) recording through numerical simulation and experiment to improve the diffraction efficiency and the resulting reconstructed images. The improvement of diffraction efficiency was more effective in garnet films thinner than the width of a fringe, and a suitable value of the assist magnetic field was identified for the improvement. In addition, MA recording improved the intensity of reconstructed images and broadened the non-error recording conditions to the low energy region. This technique shows promise in improving the reconstructed quality of magnetic hologram data.

Slow light is a phenomenon explained by low group velocity of the pulsed light. Faraday effect can be greatly enhanced in multilayered structures due to the artificial dispersion [1, 2]. Magnetophotonic crystals, as being layered nanostructures, can modulate electric filed amplitude and phase of a femtosecond pulse in time. For example, Faraday angle at the initial part of the pulse can differ from that at its tail, and from the steady-state value. In this work femtosecond dynamics of Faraday rotation is demonstrated experimentally in magnetophotonic crystals by polarization-sensitive correlation spectroscopy.

~0.8 μm thick rare-earth substituted iron garnet films were grown on single crystalline Nd:YAG substrates using pulsed laser deposition for integration of active magnetooptical Q-switches with microchip lasers.

A 1-μm thick Ce substituted yttrium iron garnet film was grown on (111) Nd:YAG substrate directly via pulsed laser deposition method for integrated magnetooptical Q-switch lasers. Magnetization properties, structural analysis using x-ray diffractions, and magnetooptical properties were characterized. The film was oriented (111) direction, and the easy axis of magnetization was oriented for in-plane of the film. The film showed a large Faraday rotation angle of −0.05 deg/μm at the wavelength of 1064 nm.

We have developed magneto-optic spatial light modulators (MOSLMs) with submicrometer-size magnetic pixels for wide-viewing-angle holographic displays (3-D-MOSLM) that are driven by the thermomagnetic recording. The holographic images were reconstructed by the magnetic hologram pattern on the MOSLM. In this paper, we have studied colorization of reconstruction images of the MOSLMs using optical space division method. This method used some 3-D-MOSLMs to represent intermediate colors. The magnetic films were polycrystalline bismuth, dysprosium, and aluminum substituted yttrium iron garnet (BiDyYFeAlG) films with perpendicular magnetization. The thickness of BiDyYFeAlG films was designed for each wavelength. The MOSLM represented (3-D) images with intermediate colors that were synthesized 3-D images with red and green colors. In addition, tones of intermediate colors were represented by controlling intensity of each reference light. These results demonstrated that 3-D-MOSLMs have promise for full-colorized holographic 3-D displays.

Hologram memory is a promising data storage technology with a high recording density and fast data-transfer rate. Magnetic garnet media such as Bi1.3Dy0.85Y0.85Fe3.8Al1.2O12 (substituted rare-earth iron garnet, SRIG) films have advantages of rewritability and unnecessity of shielding. The diffraction efficiency of these garnet films, however, is not sufficient to apply to storage devices. In this paper, we proposed a use of magnetophotonic crystals (MPC) as hologram media and calculated their diffraction efficiency. The results indicated that MPC media showed a high diffraction efficiency compared with single SRIG films, and especially the MPC medium with the structure of substituted gadolinium gallium garnet substrate / (Ta2O5 / SiO2) 2 / SRIG / (SiO2 / Ta2O5) 2 with the SRIG thickness of 3.88 m exhibited the diffraction efficiency of 0.36%. A large Faraday rotation angle and deep magnetic hologram fringe originated from the localization of light results in such a high diffraction efficiency.

The spectrally controllable enhancement of the transverse magneto-optical Kerr effect is realized in 2D hybrid metal-dielectric magnetoplasmonic metasurfaces. The light diffracted at different interfaces allows one to manipulate light phase in the condition of plasmonic and waveguiding resonance excitation controllable via the azimuthal angle. The multimodal nature of the system provides the flexible tunability of its magneto-optical response.The spectrally controllable enhancement of the transverse magneto-optical Kerr effect is realized in 2D hybrid metal-dielectric magnetoplasmonic metasurfaces. The light diffracted at different interfaces allows one to manipulate light phase in the condition of plasmonic and waveguiding resonance excitation controllable via the azimuthal angle. The multimodal nature of the system provides the flexible tunability of its magneto-optical response.

A 10-mm cavity length magnetooptically Q-switched Nd:GdVO4 laser was demonstrated using a single-crystalline ferrimagnetic rare-earth iron garnet film. To design the Q-switching system, the magnetic, optical, and magnetooptical properties of the garnet film were measured. The diode pumped solid-state laser cavity was constructed using a 190-μm-thick garnet film with 58% transmittance. The garnet film had maze-shaped magnetic domains, and the domain walls disappeared when a field of over 200 Oe was applied. Therefore, the polarization state of the transmitted light was modified by modulating the magnetization, and a Q-switched pulse output with a pulse width of 5 ns and peak power of 255 W was achieved in the 10-mm-long cavity. The physical limitation of the pulse width was discussed with the calculated results.

Collinear holography has been good candidate for a volumetric recording technology of holographic data storage system (HDSS), because of there are not only large storage capacities, high transfer rates, but also the unique configuration, in which the information and reference beams are modulated co-axially by the same spatial light modulator, as a new read/write method for HDSS are very promising. The optical pickup can be designed as small as DVDs, and can be placed on one side of the recording media (disc). In the disc structure, the preformatted reflective layer is used for the focus/tracking servo and reading address information, and a dichroic mirror layer is used for detecting holographic recording information without interfering with the preformatted information. A 2-dimensional digital page data format is used and the shift-multiplexing method is employed to increase recording density. As servo technologies are being introduced to control the objective lens to be maintained precisely to the disc in the recording and reconstructing process, a vibration isolator is no longer necessary. In this paper, we introduced the principle of the collinear holography and its media structure of disc. Some results of experimental and theoretical studies suggest that it is a very effective method. We also discussed some methods to increase the recording density and data transfer rates of collinear holography using phase modulated page data format.

Magnetophotonic crystals (MPCs) comprising cerium-substituted yttrium iron garnet (CeYIG) sandwiched by two Bragg mirrors were fabricated by vacuum annealing. CeYIG was deposited on Bragg mirrors at room temperature and annealed in 5 Pa of residual air. No ceria or other non-garnet phases were detected. Cerium 3 + ions substituted on the yttrium sites and no cerium 4 + ions were found. The Faraday rotation angle of the MPC was -2.92° at a wavelength of λ = 1570 nm was 30 times larger than that of the CeYIG film. These results showed good agreement with calculated values derived using a matrix approach.

A 14 mm cavity laser including 690 mm thick domain-controlled optical Q-switch was demonstrated. The peak power of about 2 kW, the repetition rate of 1 kHz, the pulse width of 30 ns were shown.

Magnonics is an emerging field dealing with ultralow power consumption logic circuits, in which the flow of spin waves, rather than electric charges, transmits and processes information. Waves, including spin waves, excel at encoding information via their phase using interference. This enables a number of inputs to be processed in one device, which offers the promise of multi-input multi-output logic gates. To realize such an integrated device, it is essential to demonstrate spin wave interferometers using spatially isotropic spin waves with high operational stability. However, spin wave reflection at the waveguide edge has previously limited the stability of interfering waves, precluding the use of isotropic spin waves, i.e., forward volume waves. Here, a spin wave absorber is demonstrated comprising a yttrium iron garnet waveguide partially covered by gold. This device is shown experimentally to be a robust spin wave interferometer using the forward volume mode, with a large ON/OFF isolation value of 13.7 dB even in magnetic fields over 30 Oe.

A magneto-optical Q switched laser was demonstrated using diode-laser pumped solid state laser cavity with a rare-earth substituted ferromagnetic garnet film. The Q factor of the cavity was rapidly controlled with the change of interference condition due to the magnetic domain motions in the ferromagnetic garnet. The pulse repetition was actively controlled by pulse magnetic field generator. The obtained pulse width was about 50 ns. The power was 2×107 times enhanced than that of continuous wave operation with magneto-optical Q switch.

In the big data era, the necessity for large capacity, high transfer rates and long-term data storage systems has been increased. But, the main storage media we rely on currently are magnetic technology, like hard disk drives (HDD) and tape, which life times are several years only. They cannot satisfy the demand of prolonged preservation. Optical discs based on the bit-by-bit method, such as CD, DVD and Blu-ray Disc, for storing sound, movies, photos and other digital contents are widely used in our daily life. The long-term life time is one of the properties. The optical disc should be a good candidate of data storage system for big data preservation. However, the recording density limitation of the bit recording method are looming on the horizon.

Dual-cavity magnetophotonic crystals (MPCs) based on bismuth-substituted yttrium iron garnet (Bi:YIG) have been fabricated by a bonding method, and their structural, optical and magneto-optical properties have been studied. Identical structure of bonded fractions revealed the existence of the Fabri-Perot resonances in transmission spectra of single- and dual-cavity MPCs and corresponding enhancement of the Faraday rotation. However, the bonding interface was found to be unstable because of the bonding surfaces' roughness introduced by crystallization of Bi:YIG.

The interaction of linearly polarized light with photonic crystals based on bulk and thin-film synthetic opals is studied. Experimental transmission spectra and spectra showing the polarization state of light transmitted through opals are discussed. A change in polarization is found for waves experiencing Bragg diffraction from systems of crystallographic planes of the opal lattice. It is shown that the polarization plane of the incident linearly polarized wave at the exit from photonic crystals can be considerably rotated. In addition, incident linearly polarized light can be transformed to elliptically polarized light with the turned major axis of the polarization ellipse. Analysis of polarization states of transmitted light by using the transfer-matrix theory and homogenization theory revealed good agreement between calculated and experimental spectra.

We fabricated magnetophotonic crystals (MPCs) used in electric field driven magneto-optical spatial light modulators (e-MOSLMs) with a paramagnetic garnet, which is transparent in the blue wavelength region and has a sufficient Faraday rotation angle for several applications including hologram data storage, three-dimensional displays, and optical correlators. The e-MOSLM is composed of two dielectric mirrors and one defect layer comprising magneto-optic (MO) material and electro-optic (EO) material, which controls the localized wavelength due to the change in the refractive index. The e-MOSLM utilizing MPCs allows us to use thin film paramagnetic materials, i.e., a terbium gallium garnet (TGG) and a terbium aluminum garnet (TAG), instead of a rare-earth iron garnet (RIG) because the direction of magnetization does not need to be controlled in the MO layer. We fabricated TGG thin films and MPCs with the structure of a SGGG substrate/(Ta2O5/SiO2)6/TGG/(SiO2/Ta2O5)6 by rf-magnetron sputtering. The sample produced localized peaks in the photonic band gap of the transmission spectra and an enhanced Faraday rotation angle. These results indicate that e-MOSLMs comprising an MPC with a TGG defect layer can be useful devices at the blue wavelength.

Magnetophotonic crystals and magnonic crystals having periodic structures formed band gaps by interference of waves. A one-dimensional magnetophotonic crystal (1D-MPC), which exhibits optical Tamm state at the interface between magnetic and nonmagnetic photonic crystals (PCs), shows resonant transmissivity and large enhancement of Faraday rotation at the localized mode inside the photonic band gap. We developed two-dimensional magnetophotonic crystals (2D-MPCs) on various types of templates with periodical structures. A 2D-MPC with multi-layers formed on a periodic 1D line resist template has several photonic band gaps with enhanced magneto-optical (MO) effects. In a structural garnet film formed on the opal template, a significant enhancement of MO response was obtained at edges of band gaps. Magnonic crystal with Cu metal strips formed on YIG surface showed high sensitivity of 11400 %/Oe as a magnetic sensor. In addition, enhanced MO effect was demonstrated by plasmonic composite films with noble metal particles and magnetic garnet.

We developed a magneto-optic spatial light modulator (MOSLM), for all visible wavelengths, using amorphous rare earth-transition metal (RE-TM) film. The magneto-optical elements (pixels) were made of amorphous DyFe films with perpendicular magnetic anisotropy. The the amorphous DyFe film was determined to have 22 atom percent Dy, and the Curie temperature (Tc) was found to be 343 K. For magnetic switching in this MOSLM, heating to the Curie temperature (Tc) by using a laser radiation density of 5 mJ/cm 2 and a driving current of 1 mA at all visible wavelengths were needed. In addition, we confirmed the switching speed of pixels for various laser radiation densities.

AgBr-doped silsesquioxane–titania films with a thickness of approximately 5 μm were prepared using a sol–gel technique. The dopant AgBr crystals were converted into very small Ag nanoparticles (mainly several nanometers) upon blue laser irradiation, leading to an increase in the absorption of the film in the visible region. An excess of Ag + ions in the film was required for the conversion of AgBr into Ag upon blue laser irradiation. A maximum diffraction efficiency of 0.03% was achieved after two-beam interference exposure with a blue laser for 1300 s. These results imply that the films are suitable for use as holographic materials.

Establishment of processing technology for multifilamentary coated conductors (CCs) is a key issue for superconducting electric power applications from the viewpoint of AC loss reduction. On the other hand, CCs sometimes have local inhomogeneity in the superconducting layers, and that will cause a current blocking in a filament or inhomogeneity of critical current among filaments in a multifilamentary CC. Therefore, we need an assessment method for local electromagnetic behavior on AC loss properties of CCs. In this study, we developed a method for visualizing time-dependent AC loss distribution in CCs by using scanning Hall probe microscopy. We succeeded in visualizing local current density, electric field and loss density simultaneously with a spatial resolution of a few hundred micrometers. The measurement system has possible scanning area of 150 × 50 mm 2 and current capacity of 500 A. This enables us to discuss the local electromagnetic behavior on a practical scale of CCs. We believe that this visualization method will be a very powerful tool to estimate the feasibility of processing technology for multifilamentary CCs.

Zinc oxide (ZnO) is a promising material for combining with magneto-optic (MO) materials because it can propagate stable exciton-polaritons, with velocities considerably lower than that of photons in a vacuum. This study investigated the influence of sputtered ZnO and Al:ZnO top layers on MO responses of a bismuth-substituted yttrium iron garnet (Bi:YIG) film. The ZnO top layer modulated the Faraday rotation and magnetic circular dichroism (MCD) of the Bi:YIG around the exciton resonance wavelength of ZnO at 369 nm. Furthermore, Al-substituted ZnO, which is a conductive ZnO, also changed the MO effects around the exciton resonance wavelength. These results imply that the exciton-polaritons in ZnO affect the MO interaction, because of their considerably low group velocity. The results suggest potential for controlling the MO response via excitons.

We present a study of a Fano resonance between a narrow Bragg band and disorder-induced continuum in photonic crystals where the continuum is either of the broad band Fabry-Perot scattering in an imperfect one-dimensional photonic crystal or Mie scattering in an imperfect three-dimensional photonic crystal. Our experimental studies of synthetic opals have demonstrated how the Fano resonance may lead to a transmission spectrum exhibiting a Bragg dip with an asymmetric profile or a Bragg rise.

We investigated a fabrication process and optical properties of electro-optic (EO) light modulators with Fabry-Perot structure, which consisted of PLZT [(Pb0.91, La0.09)(Zr0.65, Ti0.35)O3] thick films by aerosol deposition method. A supernatant elimination process for small size PLZT powder with diameter of 0.125-0.175 μm was effective in order to obtain a transparent film. In the fabricated Fabry-Perot type EO light modulator with a ITO (Indium Tin Oxide))/PLZT/ITO defect layer, a wavelength of resonant localized mode was shifted about 1.0 nm from 788 nm by applying an electric field of +400 kV/cm in reflectance mode, and consequently the reflectance difference of 7.2 % was observed. The Fabry-Perot type EO light modulator had the advantage of contrast of light in the reflection mode.

To obtain enhancement and wavelength tuning of the magneto-optical (MO) response associated with the localized surface plasmon resonance (LSPR), bismuth-substituted yttrium iron garnet (Bi:YIG) composite films with Ag particles and Au-Ag alloy particles were studied. The Bi:YIG composite film with Ag particles did not show any enhancement of Faraday rotation. On the contrary, the Bi:YIG composite films with Au-Ag particles exhibited the enhancement of the MO response for different wavelengths of LSPR. We observed the enhanced Faraday rotation for the Bi:YIG/Au-Ag composite films with volume ratios of Ag up to 0.6. In addition, when changing the volume ratio of Ag, the peak of rotation shifted to short wavelengths. Disappearance of enhancement for the Bi:YIG/Ag composite film can be addressed to modifying the interfacial medium between the MO host and Ag. Since chemically active Ag particles can form nonmagnetic Ag compound shells separating Bi:YIG and the plasmonic subsystem, the LSPR of Ag particles did not affect the MO response. The Au-Ag alloy particles were chemically stable in the Bi:YIG/Au-Ag composite films.

Bismuth-substituted yttrium iron garnet (Bi:YIG)-based magnetophotonic crystals (MPCs) with 2D structure were fabricated using autocloning of various patterns. We studied structural properties of these MPCs and evaluated their magneto-optical responses. Enhanced Faraday rotation of the same sign as that for conventional Bi:YIG films and of the opposite sign was observed for 2D patterned Bi:YIG films fabricated on top of opal films.

This paper introduces the self-generation vibration sensor using levitated magnet. We have verified experimentally and theoretically that this sensor is available in frequencies of 5 to 25 Hz. The frequency response of sensitivity shows the maximal value at certain frequency. These sensitivities obtained 3.9 V/G at 11 Hz for levitated magnet of neodymium and 3.0 V/G at 10 Hz for the magnet of samarium cobalt. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 1–8, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20525

We fabricated a planer type tunnel structure with Au nanoparticles that were formed between two electrodes on a substrate. The mean diameter of the Au nanoparticles was 7.3 nm, and the wavelength of the localized surface plasmon resonance was about 544 nm. Tunnel current flowing through Au nanoparticles between two electrodes changed by illumination of a laser beam. A large change of tunnel current was observed when a plane of linear polarized light (electric field) corresponded to the direction of electron tunneling through Au nanoparticles; the change of tunnel current obtained by laser illumination with a wavelength of 532 nm was larger than the one with a wavelength of 633 nm. The dependencies on wavelength and polarization of laser beam suggest that the change of tunnel current occurs not only by the thermal effect but also by the localized surface plasmon resonant effect. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.