bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct butt coupling type of LED module with multiple output fibers
Authors: Sunada Tadasu 
Published: July 2007

AbstractWith regard to domed LEDs, this paper describes an LED module with multiple output fibers arranged radially around a source using a direct butt coupling system. It is found that the optical coupling efficiency is improved by tilting the fiber so that it is oblique to the source. This is done also for the direct butt coupling LED module without lens, and an optimum module structure is established using this coupling method. A detailed analysis is carried out on the fiber coupling efficiency for domed LEDs with various active layer depths d, and the optimum active layer depth to realize multiple and high outputs is estimated to be dO = ∼ 45 μm considering the SiO2 insulating layer. A fabricated LED module with ten output fibers using a domed LED (dome radius of 200 μm) with the depth of d = 45 μm, gives a high optical power of about 120 m in each fiber.
Tunnel‐oxide breakdown characteristics of floating‐gate‐type EEPROM
Authors: Sato Kazuo , Fukuzaki Yoshiki , Hatakeyama Shinichi , Ikeda Nobuyuki 
Published: July 2007

AbstractThis paper aims at the analysis of the breakdown characteristics and the mechanism of the tunnel oxide breakdown by the iterative rewriting of floating‐gate‐type EEPROM. The relation of number of rewritings until the tunnel oxide breakdown to the rewriting condition and the process condition is investigated. As a result, an approximate relation logNαQfgis derived, whereNis the number of rewritings until the tunnel oxide breakdown andQfgis the tunnel charge in rewriting. It was seen also thatNis nearly proportional to the life of the tunnel oxide determined from TDDB characteristic. It is estimated that the major cause of the tunnel oxide breakdown is the trap of the electron in the tunnel oxide. The trapped electron can easily be released by the thermal treatment of some 5 hours, improving the life of the number of rewritings until breakdown.
Transient temperature response of avalanche diodes against lightning surges
Authors: Satoh Hidetaka 
Published: July 2007

AbstractAvalanche diodes are used frequently as lightning surge protectors because of their high‐speed response and constant voltage suppression characteristics. In this paper, a transient temperature response analysis is carried out with a view to determining the relationship between the temperature and the failure under the application of lightning surge. In the analysis, the nonsteady‐state thermal conduction equation is solved by the finite difference method. The nonlinear elements included in the analysis are the temperature dependences of the thermal conductivity thermal capacity and breakdown voltage of the avalanche diode. It is confirmed that the theoretical results of the temperature and the voltage drop of the avalanche diode agree well with the measured data. It is found that the peak temperature in the avalanche diode under the application of a standard lightning surge (waveform: (10/200) us and (10/1000) us) appears near the half‐value decay time and that the failure of the avalanche diode depends on the peak temperature, and the critical failure temperature is estimated to be about 490 degrees.
Electromagnetic fields in circular bends of slab waveguides
Authors: Yamada Ryuji , Morita Nagayoshi 
Published: July 2007

AbstractA method for rigorous analysis of transmission in and radiation from a uniformly bent finite‐length section of a slab wave length is proposed. The eigenmodes with continuous eigenvalues, which are similar to the radiation modes of the straight waveguide, are defined first for expressing fields in circular bends of slab waveguides, and a kind of orthogonality relation for these eigenmodes is derived. The spectral integral of these eigenmodes can give a rigorous expression of fields in circularly bent sections, which is proved by using the radiation condition and the Fourier transformation technique. The theory is applied to the analysis of transient phenomena of fields in the uniformly bent section connected to the straight section. Numerical examples of transition of field distributions and radiation patterns are presented and the results are discussed in detail.
Bridge measuring method of active impedance of crystal oscillator circuits
Authors: Toki Masahiro , Hattori Shinichi , Nakano Hirokazu 
Published: July 2007

AbstractCrystal oscillator circuits have been used widely in such electronic equipment as communication devices and measurement instruments. However, until the crystal is connected, usually it is uncertain if the circuit oscillates or it is difficult to determine how one adjusts the circuit for a desired oscillation frequency. With a view to alleviating these situations and improving the design method for the crystal oscillator circuits, a method is developed for accurately measuring with a bridge the two‐terminal impedance (equivalent series capacitance and negative resistance) of the active circuit seen from the connecting terminal of the crystal. A bridge measurement method for the small‐signal negative resistance related to the starting characteristics of the oscillator is discussed. In conjunction with the bridge measurement developed earlier for large signal operations under oscillation, a complete bridge measurement has become possible from the small signal region to the large signal region. The present bridge measurement method is useful in providing a basic specification for the active circuit side for a given crystal. It is also shown that the present bridge method is useful for evaluation of accuracy of other measurement instruments such as impedance analyzers.
Scattering of electromagnetic plane waves by two arbitrarily oriented conducting plates
Authors: Shimoda Michinari , Itakura Tokuya 
Published: July 2007

AbstractA two‐dimensional scattering problem of electromagnetic waves is analyzed by two conducting plates which are arranged arbitrarily through the problem formulation utilizing the mutual fields. The formulation based on the representation of the scattered fields by one plate is shown. The scattered waves were represented by solving simultaneous Wiener‐Hopf equations which are satisfied by every scattered field. By using the saddle‐point method, their approximate solutions and diffraction patterns in a far field are calculated, and the results are compared with numerical results by other methods. Using the present formulation, it was possible to solve scattering for a system of conducting plates considering multiply scattered waves when the edges of the plates are separated at least one wavelength for two plates with greatly different yet finite widths.
Theoretical analysis of the cerenkov laser using a nonlinear dielectric waveguide
Authors: Ishido Yoshinari , Shiozawa Toshiyuki , Ibaraki Susumu 
Published: July 2007

AbstractConsider a Cerenkov laser, using for the slow‐wave structure a dielectric waveguide whose substrate consists in a nonlinear dielectric presenting the self‐focusing effect. The characteristics of the Cerenkov laser specified in the foregoing are investigated theoretically for the two‐dimensional model which takes into account the field distribution in the transverse direction.First, the dispersion relations are considered for the electromagnetic wave modes (TM waves) propagated along a two‐dimensional nonlinear dielectric waveguide. Then the dispersion relations are discussed for the coupled electromagnetic fields in the Cerenkov laser using the nonlinear dielectric waveguide. Finally, the spatial growth rate of the growing wave obtained from the dispersion relation for the coupled fields derived in the foregoing is investigated numerically in detail. From the forementioned discussion, it is found that the spatial growth rate for the Cerenkov laser treated in this paper is improved compared to the Cerenkov laser for which the slow‐wave structure is composed of linear dielectrics only.
Drawing condition dependence of pure‐silica‐core single‐mode fibers
Authors: Hanawa Fumiaki , Hibino Yoshinori , Horiguchi Masaharu 
Published: July 2007

AbstractThe conditions have been investigated for drawing the SiO2 core/F‐SiO2 cladding single‐mode optical fiber which is expected to have the lowest optical loss among the silica optical fibers. In this type of optical fiber, the softening temperature of the core is higher than that of the cladding, and the softening temperature distribution is different from that of the GeO2‐SiO2 core/SiO2 cladding‐type optical fibers. In this study, the residual stress in the fiber during drawing was investigated theoretically and experimentally, considering the softening temperature difference between the core and cladding. The following results were obtained. In the SiO2 core single‐mode optical fiber, the tensile stress remains in the core where it is proportional to the drawing tension and inversely proportional to the area of the cross section. The residual stress influences the refractive index of the core and the cut‐off wavelength, but degrades the propagation loss characteristic. Finally, this paper will show that: (1) this optical fiber belongs to the F‐SiO2 core/F‐SiO2 cladding type from the viewpoint of the material, and (2) the depressed‐type structure is the most suitable.
Transmission characteristics of modes in dielectric slab waveguides with finite‐length, uniformly bent section
Authors: Yamashita Ikuo , Morita Nagayoshi 
Published: July 2007

AbstractThis paper investigates the radiation and propagation of electromagnetic fields in a uniformly bent section of a rib waveguide connected with the straight section when guided modes are incident from the straight section. The analysis is based on a method in which fields in uniformly bent sections are expressed in terms of a spectral integral of eigenmodes with continuous eigenvalues. Fields propagated along a uniformly curved slab waveguide with finite‐length also are analyzed in detail using the same method for a full numerical investigation of mode transmission and mode conversion characteristics for the slab waveguide structure where two straight waveguides are connected via one finite‐length, uniformly curved section.
Multisensor module using magnetic semiconductor ferrite
Authors: Seki Kyoshiro , Tsunekawa Yoshitaka , Osada Hiroshi , Shida Jun‐Ichi , Murakami Koichi 
Published: July 2007

AbstractThere are several compound magnetic semiconductors, but they are not very practical because their Curie temperature is below room temperature. The magnetic semiconductor ferrite (MSF) has a ferromagneticity at room temperature as well as a semiconducting resistance and permittivity. The magnetic characteristics of the MSF depend on temperature but not on humidity and gas concentration. Also, the permittivity depends on the temperature, humidity and combustible gas concentration.As an application of these characteristics, a multisensor module is constructed which contains temperature, humidity and gas sensors. In the conventional method, a number of sensors corresponding to the kinds of quantities measured are required. However, in the present system, only one MSF can detect temperature, humidity and combustible gas concentration. Therefore, the number of sensors needed is small and the equipment is simplified. In addition, since these quantities measured can be converted to RF, the system is suited for digital measurement.
Fabrication of high‐quality Nb/AlOx/Nb Josephson junctions
Authors: Mori Hiroyuki , Hirano Mikio , Hatano Yuji , Kawabe Ushio , Yamada Hirojo , Tarutani Yoshinobu 
Published: July 2007

AbstractThis paper studies an Nb/AlOxNb junction, and the cross‐sectional shape of the junction interface and the surface state are observed. It is found that the AlOxfilm used as the tunnel barrier layer is locally nonuniform and is dependent on the shape of the Nb film forming the lower electrode. This dependence is a factor causing junction characteristic variations. Further, the fabrication method of the Nb electrode film is discussed. It is important to form a flat and dense Nb film with few particle boundary trenches when fabricating the lower electrode film. A high‐quality Nb/AlOx/Nb film can be fabricated withRj/Rnn> 20 and a fluctuation ofImoof ±6%. Also, the Nb/AlOx/Nb junction of 1.5 μm2with improved junction characteristics is applied to a 3 k logic gate array. The delay time of the 826‐stage OR gate is found to be 10.5 ps/gate.
Transient analysis of ferrite phase shifters in rectangular waveguide in three‐dimensional space
Authors: Kukutsu Naoya , Yoshida Norinobu , Fukai Ichiro 
Published: July 2007

AbstractNumerous nonreciprocal devices using magnetized ferrites have been developed for microwave and millimeter‐wave circuits. Further, improvement of the material characteristics and development of new device structures have been studied with a view to high‐density implementation of the devices along with the development of microwave integrated circuits. With the advances in high‐speed digital techniques studies of transient characteristics became necessary. Hence, it has become indispensable to carry out a three‐dimensional (3‐D) analysis including the coupling with other devices as well as the time response analysis including the transient characteristics in the development of the devices using ferrite.Recent advances in phase array antennas have made the analysis of the characteristics of the rectangular waveguide phase shifters important with a view toward improvement. These phase shifters have several formats such as the local loading of a waveguide with several ferrite slabs and the use of residual magnetization. This paper makes use of the spatial network method which has been demonstrated to be effective for 3‐D time‐response analysis of electromagnetic fields. This method is used for the analysis of three types of phase shifters with one and two ferrite slabs and a toroidal ferrite. It is demonstrated that the structures can be treated systematically and the validity of the method is confirmed by comparison with the analytical solution.
Finite–element analysis of waveguide transfer problem—field connection by using the Galerkin method
Authors: Maruta Akihiro , Matsuhara Masanori 
Published: July 2007

AbstractAs a method of analysis for the waveguide transfer problem, the Galerkin method with the waveguide eigenmode functions as the weighting functions is proposed for connection of the electromagnetic field at the discontinuity represented by the finite‐element method with the waveguide electromagnetic field represented by the eigenmode expansion at the junction between the waveguide and the discontinuity. In this method, there is no specific restriction between the number of expansion modes of the field in the eigenmode expansion method and the number of basis functions of the field by the finite‐element method on the junction. The matrix equation to be solved is symmetric and the matrix representing the scattering at the discontinuity can directly be analyzed numerically. As specific examples, the present method is applied to right‐angle corner bend and a waveguide‐type dielectric bandpass filter. It is confirmed that the results agree well with those obtained by the conventional method.
A construction of pattern classification system using direct‐drawn computer‐generated fourier hologram
Authors: Kajiki Yoshinori , Takahashi Hideya , Matsushita Kenji , Shimizu Eiji 
Published: July 2007

AbstractThis paper considers the construction of the trainable classification system by redrawing a computer‐generated Fourier hologram (CGFH), which is based on the previously proposed method of pattern classification using CGFH. CGFH has a flexibility that can be synthesized by computation, and it is expected that a flexible pattern classifier will be constructed if the adjustment of the weight in the proposed system can be realized through the redrawing of CGFH. However, if CGFH is constructed by the traditional method by the size‐reduction of a photograph, the required processing such as size reduction and developing will make it difficult to redraw CGFH on the optical system.To solve this problem, this paper considers a system which generates CGFH directly on the glass substrate, by a laser beam scanning on a thin film. Using the proposed direct‐drawn CGFH (DDCGFH) system, a basic experiment is made on the construction of the pattern classification system by learning (i.e., redrawing of CGFH).First, an investigation is presented on the coding of CGFH suited to the DDCGFH construction system, together with a result of experiment for DDCGFH. Then the construction of the classification system by redrawing DDCGFH is considered. The algorithm and the result of basic experiment are reported.
Formation of silicon oxide by the low‐temperature process and its application to electron devices
Authors: Nomura Shigeru , Kitamura Naoko , Yoshino Masaki , Nanjo Junji , Ishibe Shinzo , Kanemaki Youichi 
Published: July 2007

AbstractThe technology of forming silicon oxide film at low temperature was developed and the application of the oxide film to electronic devices was investigated. Silicon oxide was formed by anodic oxidation of silicon at room temperature. The anodic oxide was Si‐rich in the as‐grown state.When the anodic oxide film was annealed at 600°C in hydrogen atmosphere, followed by annealing at 450°C in the same ambient, the film became stoichiometric SiO2 and the SiO2/Si interface condition was improved because of the saturation of the unsaturated Si atoms at the interface. These mechanisms were evaluated by IR, AES, and SIMS analyses. The SiO2/Si interface was investigated by the degree of atomic dimension using TEM. As a result, it was found that the overall interface could be regarded as flat but it had local dents.After annealing, a transition region of one or two atom layers in thickness existed at the interface. It was found that the electrical properties of the annealed anodic oxide were comparable with those of an oxide film grown thermally by the MOS C‐V measurement. The input/output characteristics of an MOSFET with a gate oxide formed by this anodic oxide indicated that the anodic oxide formed at low temperature could be used for electronic devices.
Analysis of surface current on a circular cylinder with a large radius by boundary element method combined with fft
Authors: Kusunoki Masahiro , Takenaka Takashi 
Published: July 2007

AbstractAn effective numerical method is presented for the induced current distribution on a conductor surface when electromagnetic waves with general complex amplitude such as Gaussian beam waves are incident on a perfectly conducting circular cylinder. Up to the radius of the wavelength, the surface current can be analyzed accurately by the boundary element method. For a further increased radius, the execution time for calculation is increased or the memory storage capacity becomes insufficient. The direct method by obtaining inverse matrices becomes computationally difficult.It had not been known that the coefficient matrix is a cyclic matrix for the resulting matrix equation when the integral equations of the surface current are made discrete. This matrix equation can be solved effectively through a discrete Fourier transform without obtaining the inverse matrix. Examples of numerical calculations are shown in which the method presented here was applicable for a radius which ranged from a wavelength to several tens of wavelength.
Effects of microstructure on magnetic anisotropy of CoCr thin films
Authors: Honda Yukio , Futamoto Masaaki , Saito Shinichiro , Yoshida Kazuetsu 
Published: July 2007

AbstractTo investigate the effects of micro‐structure on the magnetic anisotropy of CoCr perpendicular magnetic recording film, magnetic torque curve measurement and transmission electron microscope observation were carried out. Two kinds of samples were prepared, one was deposited directly on polyimide base film and the other was deposited on a Ge underlayer by vacuum evaporation. The dependence of the torque curve on the film thickness was evaluated and the following results were obtained.In a CoCr film deposited on a polyimide substrate, Ku2 decreases with an increase of film thickness. This is because in the initial growth layer on the polyimide substrate, the c‐axis (easy axis of magnetization) orientation of CoCr grains is poor and the distribution of the grain size is somewhat random.As the film thickness increases, the c‐axis orientation improves. In these CoCr films, magnetization hardly saturates under the applied magnetic field, resulting in a large amount of Ku2. In a film deposited on the Ge underlayer, Ku2 is small and remains constant regardless of film thickness.In this CoCr film, the grain size is uniform and the c‐axis orientation is excellent. As a result, the film is magnetized easily along the applied magnetic field and Ku2 is thought to be constant regardless of film thickness.
Anodic oxidation and mass transport in multilayered metal films
Authors: Noya Atsushi , Sasaki Katsutaka , Umezawa Toshiji , Dobashi Tsuyoshi 
Published: July 2007

AbstractIn a fundamental investigation of the oxidation of multilayered metal films and accompanying mass transport, Al/Metal/Al model films (in which the metal was Hf, Nb, Mo and Au) were prepared and anodized and were used to investigate oxide growth and mass transport by Auger electron spectros‐copy. Depending on the metal in the middle layer, some specimens exhibited a sequence of oxide layers different from the initial sequence of layers, and in others a layer had been lost by mass transport.Physicochemical properties providing convenient measures of the chemical properties or bonding characteristics of the metals in question were identified and compared. The anodization results and mass‐transport behavior were well explained in terms of these measures.
Peak shift characteristics in high density magneto‐optical recording
Authors: Yamamoto Manabu 
Published: July 2007

AbstractThis paper presents the peak shift characteristics caused by intersymbol interference and medium defects and their long‐term change and fluctuation in a recording and playback system. Through an analysis of the waveform of the playback differential signal and the effect of the signal amplitude fluctuation on the peak shift under superimposed noise, the intersymbol dependence of the peak shift is obtained.In addition, the signal amplitude fluctuation due to medium defects and the long‐term change of the bit error rate in a high‐temperature and high‐humidity environment are obtained experimentally so that the effect of medium defects and their long‐term change on the peak shift is found. The effect of variations in the external magnetic field and the erasing power on the reduction of the signal‐to‐noise ratio (SNR) is found. Also found is the effect of variation in the recording power on the peak shift shift in RZ and NRZ recording.From this, it is shown that the dependence on the external magnetic field is especially significant in the effect of the variation of the recording and playback system and that the peak shift can be reduced in RZ recording through the use of narrow pulse width recording.