bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resonance characteristics of whispering gallery modes on a dielectric disk
Authors: Tomabechi Yoshiro , Matsumura Kazuhito 
Published: July 2007

AbstractResonance and loss characteristics of whispering gallery modes in a dielectric disk resonator are discussed three‐dimensionally by using an approximate variable separation method. A radius of the disk is sufficiently large compared to a wavelength. A cylindrical function with a complex order and argument whose absolute values are much larger than unity is included in an eigenvalue equation.In this paper, the eigenvalue equation is solved analytically by using a newly developed calculation method of the cylindrical function. As a result, resonance and loss characteristics of the dielectric disk resonator in a wide frequency ranging from a microwave to optical wave are understood. The present method can be applied to a whispering gallery mode resonator made of lossy dielectric materials. Therefore, one can obtain a radiation loss separately from a dielectric loss based on a loss tangent of the materials.
Analysis of 1 × 3 coupled‐waveguide optical power dividers by the implicit finite‐difference method
Authors: Yamauchi Junji , Ando Takashi , Nakano Hisamatsu 
Published: July 2007

AbstractOptical 1 × 3 power dividers composed of coupled waveguides are analyzed using the implicit finite‐difference method and the low‐loss configuration with reduced size is investigated. First, to check the accuracy of the method, the mismatching loss of the eigenmode of a straight waveguide is evaluated and it is verified that the error does not accumulate with the propagation distance.Next, the characteristics of 1 × 3 power dividers using coupled waveguides inclined with respect to each other are investigated and the range of the tilt angle and the effects of the angular error upon power distribution are clarified. To widen the tilt angle, which results in reduced‐size dividers, the corner bends with modified refractive‐index distribution are introduced. As a result, the loss of a 3‐degree tilt angle divider is found to be reduced by more than 1.5 dB due to the introduction of the corner bend with modified refractive‐index distribution.
Hairpin‐shaped stripline split‐ring resonators and their applications
Authors: Yabuki Hiroyuki , Endo Haruyoshi , Sagawa Morikazu , Makimoto Mitsuo 
Published: July 2007

AbstractThe split‐ring resonator made of an open‐ended ring‐shaped stripline connected at its ends with a lumped element capacitance has already been used in practice as a resonator element for an oscillator. If this lumped element capacitance is replaced with a distributed capacitance, the structure can be modified to a hairpin‐shaped resonator with a distributed coupling circuit.This paper studies such fundamental characteristics as the resonant condition of this resonator. In addition, by using its characteristics, applications are proposed for multiple‐stage filters and push‐push oscillators. The design data are organized and a trial fabrication is carried out for verification. The experiment is carried out in the L band. From the results, it is found that the resonator of this configuration is small in size and has high degrees of freedom. The structure can be applied to MIC or MMIC at much higher frequencies.
Finite‐element analysis of planar electron waveguides
Authors: Kaji Ryosaku , Hayata Kazuya , Koshiba Masanori 
Published: July 2007

AbstractAs a method for guided mode analysis of a planar electron waveguide with an arbitrarily shaped potential profile and an arbitrary effective mass profile, an analysis method based on the finite element method is proposed. The methods for computation are presented for the phase constant, mode confinement factor, and group velocity of the guided mode. Specifically, the present method is applied to rectangular and parabolic electron waveguides so that the validity and effectiveness of the method are presented.
Synthesis of symmetrical double‐barrier structures and analysis of their resonant tunneling characteristics
Authors: Kato Fumio , Iwasaki Hideo 
Published: July 2007

AbstractAs a first step toward establishing a methodology for a quantum effect device design, the resonant characteristics in a symmetrical double‐barrier structure were studied and its synthesis problem was investigated. It was found that the resonance levels are not always dependent on the barrier width and the well width. Some are dependent on only one of them or on neither of them. By deriving an equation explicitly expressing each resonance level or its upper and lower bounds, the profile was found. In the synthesis problem, with the barrier width and the well width as variable parameters, the realization of one level given arbitrarily was discussed and the methodology was presented. It was shown that higher‐order resonances of second and third orders can be realized. A synthesis method is presented.
Analysis of ferrite slab waveguides with resistive strip gratings
Authors: Ozaki Akira , Asai Masamitsu , Yamakita Jiro , Sawa Shinnosuke 
Published: July 2007

AbstractAn analysis and numerical calculation of a leaky wave propagating in a magnetic waveguide with a resistive strip grating are presented. The analysis is formulated by a matrix. A characteristic equation of the waveguide is derived by applying the Galerkin method to a resistive boundary condition expressed by a Green function in a spectrum region for a magnetic material and also by a surface current density which is expanded in terms of functions.A numerical calculation is made for a leaky region where the effect of a surface resistance and magnetic loss are considered. A step function and a function with a singularity are used in expanding a surface current density. The validity of limiting expansion terms and the convergence of solutions are discussed for not only a propagation constant but also a root mean square error of the resistive boundary condition and a surface current density.
Chemical beam epitaxy growth of gainasp/inp and application to surface‐emitting lasers
Authors: Uchida Takashi , Yokouchi Noriyuki , Miyamoto Tomoyuki , Koyama Fumio , Iga Kenichi 
Published: July 2007

AbstractThis paper discusses the doping characteristics and the crystalline quality of GaInAsP/InP grown by a chemical beam epitaxy method important for realizing surface‐emitting lasers of long wavelengths. A good controllability of Be doping and very little degradation examined by photoluminescence are found in GaInAsP and InP for a wide range of Be dopants. The crystalline quality of a double heterostructure is improved by optimizing a growth condition. As a result, a minimum threshold current density of 5 kA/cm2is obtained for edge‐emitting lasers at a 1‐μm thick active layer.Under the optimized condition, a circular mesa‐cap surface‐emitter laser is fabricated. The minimum threshold current of 2.7 mA and the threshold current density 450 A/cm2are obtained at 77 K under the CW operation. A pulsed operation of an SE laser with GaInAsP/InP multilayer reflector is confirmed near room temperature. The applicability of the chemical beam epitaxy method for growing an SE laser is described.
A study on partial response system in digital magnetic recording
Authors: Okamoto Yoshihiro , Osawa Hisashi , Takigawa Kiyoshi , Ono Kazuo 
Published: July 2007

AbstractThe partial response (PR) system is believed to be an important scheme for signal processing in high‐density digital magnetic recording. This paper discusses the improvement in performance of the PR(1, 0m ‐ 1, ‐1) system, which is one of the PR systems. With increasing recording density, a high‐frequency noise due to the compensation for a high‐frequency attenuation increases significantly and accordingly a signal‐to‐noise ratio (SNR) becomes lower, which is also tied to the inherent high‐frequency boost characteristics of PR(1, 0m ‐ 1, ‐1).Also proposed is a new PR system and a signal‐detection method by which one can expect to improve the characteristics by using an intersymbol interference for a signal detection caused by suppressing a high‐frequency noise through a bandwidth limitation in PR(1, 0m ‐ 1, ‐1). For the proposed system and the conventional PR(1, 0m ‐ 1, ‐1) system, the SNR required to achieve a bit error rate of 10−8 is obtained. It is confirmed that the proposed system provides a better performance than the conventional system.
Composition analysis of anodic SiO2/Si interface region using the XPS method
Authors: Nanjo Junji , Kawahara Tadashi , Mostafa Kamal Abu Hena , Nomura Shigeru , Kitamura Naoko 
Published: July 2007

AbstractSilicon oxide film, which has been used as a protective and active layer in Si devices, has been fabricated electrochemically at room temperature. The fabrication method is anodization combining a constant current and constant voltage mode. Ethylene glycol was used as an electrolyte. To improve the characteristics of silicon oxide film and also the interfacial property of the film with an Si substrate, the oxide film was annealed under hydrogen atmosphere. The depth profile of an atomic concentration was measured by X‐ray photoelectron spectrum (XPS). The thickness of the oxide film was varied by etching with p‐etchant. The as‐grown film is composed of nonstoichiometric silicon oxide of sub‐oxides, SiO2, SiO, and Si2O3, which are nonuniformly present near the Si‐oxide interface up to 40 Å from the Si surface. The remainder of the oxide is stoichiometric amorphous SiO2. After annealing, the amount of sub‐oxides decreases.
New integral equations for designing dielectric waveguide bend circuits: Guided‐mode extracted integral equations
Authors: Tanaka Kazuo 
Published: July 2007

AbstractFor the new integral equation proposed previously by the author for the discontinuity problem in a dielectric waveguide, the nature of the numerical solution based on the moment method (boundary element method) is studied in detail by applying the method to a bend of a dielectric slab waveguide with an arbitrary shape. The necessary discretization range for the desired results, the location of the virtual boundary and the effect of the convergence of the field on the results are studied in detail by comparison with rigorous solutions. Further, dielectric bends of various shapes for reducing the radiation loss are analyzed. It is shown that an optimum shape can be obtained by means of the new integral equation.
Analysis of obliquely propagating waves along dielectric grating waveguide with square corrugation
Authors: Matsumoto Keiji , Rokushima Katsu , Yamakita Jiro 
Published: July 2007

AbstractIn a slab waveguide with a rectangular dielectric grating, the analysis of an optical wave propagating at an arbitrary angle with respect to the grating vector is formulated by means of the spatial harmonic expansion method. For this guided‐wave problem, a hypothetical excitation condition is introduced for determination of the direction making the attenuation of the propagation wave maximum and the phase velocity direction.Hence, the complex propagation constant to be derived is determined as the singular solution to the three‐dimensional guided‐wave problem dependent on three directional relationships on the grating vector, maximum attenuation, and phase velocity. In the analysis, the solution can be made more accurate by increasing the orders to truncate the permittivity profile and the spatial harmonics, since no approximations other than these truncations exist.In the numerical examples, the accuracy of the solution is shown for the waveguide for which the grating vector direction and the maximum attenuation direction coincide. In addition, it is pointed out that there exists a peculiar stopband due to the coupling between the TE and TM waves as well as a radiation region of the leaky wave caused by the oblique propagation. Further, the radiation is considered in the case where a leaky wave is generated and the numerical results are presented for the radiation efficiency.
Long‐term aging effect on led circuit with fe‐based amorphous current transformer
Authors: Fukuhara Minoru , Kakehashi Hidenori , Ohta Yukihiko , Fukunaga Hirotoshi , Ninomiya Tamotsu 
Published: July 2007

AbstractThe current transformer used in a conduction detector switch circuit for lighting up an light emitting diode (LED) for detection of load current in distribution lines has to be small and of low excitation current. Since field‐annealed Fe‐based amorphous cores have high saturation magnetization and the squareness ratio of a hysteresis loop and low coercive force, current transformers that are superior to ferrite cores can be designed. Furthermore, in cases where reliability is required over long periods such as in LED lighting circuits, for the purpose of design, it is necessary to predict what influence is exerted on the circuit characteristics by the aging variations of the amorphous magnetic characteristics [1, 2]. Therefore, recently, based on a prediction method of dc coercive force researched by the present authors [3], aging variation prediction was carried out on ac (60 Hz) coercive force.Next, the ac magnetic characteristics of Fe‐based amorphous cores were approximated by Potter's model [4], LED circuit analysis was carried out by application in a Spice program, and good agreement with experimental results was confirmed. In addition, using the prediction values of aging variation of the cores, on deducing the effect of influence on circuit characteristics it was found that the degradation of LED circuit characteristics at 100°C and 106 hours of elapse was minimal, and it is possible to predict the maintenance of excellent characteristics better than in the case of ferrite cores.
Construction of electromagnetic scattered fields from smooth dielectric cylindrical objects with relative‐refractive‐index less than 1 by using the extended ray theory
Authors: Ohmori Toshiyuki , Ikuno Hiroyoshi , Nishimoto Masahiko 
Published: July 2007

AbstractThe problem of scattering by a cylindrical dielectric having a relative index of refraction smaller than unity with a smooth boundary is analyzed by the extended ray theory (ERT). According to the ERT, the scattering process of the electromagnetic wave can be analyzed systematically if the scattered field is analyzed with the six elementary processes described in regard to the geometrical optics phenomena and the diffraction phenomena. Hence, for each elementary process, the scattering center was derived and the amplitude and phase of the ray are evaluated. The amplitude is computed as the product of the scattering coefficient of the canonical problem and the amplitude derived geometrically from the energy conservation law.The phase is determined from the optical path length of the ray and the propagation coefficient of the canonical problem. Then the scattered field can be constructed by superposition of the rays of the scattering processes obtained from each elementary process and their combinations. In this problem, the diffraction effect generally is weak. Hence, the scattered field is constructed from the geometrical optics rays. As a typical example, the transient scattering responses by a circular dielectric cylinder and a dielectric cylinder with a concave‐convex boundary were constructed by the ERT. The results agree well with the reference solutions. It is demonstrated that the electromagnetic scattered field in this problem can be analyzed by the real and complex geometrical optics rays.
Optimization of disk array subsystem using small disks
Authors: Sakurai Norihiko , Kishigami Junichi 
Published: July 2007

AbstractOne of the recent trends in the development of magnetic disk devices is the advent of small disks. The small disk has a great influence on the performance of the magnetic disk subsystem.This paper assumes that the small‐sized magnetic disk subsystem will be introduced around 1995 and formulates the relation between the disk size and the performance/cost. The disk array subsystem architecture using small disks is considered, and the evaluation is made based on the number of disks for the parallel synchronous transfer.As to the file performance, code and image information are considered and the condition for the subsystem with the best cost/performance ratio for each kind of information is shown. It is shown that small disks of 1 to 2.5 inches are being developed rapidly at present aiming at the application to the portable equipment and will experience the widest area of application. The requirement for the magnetic disk device, e.g., the relation between the rotation for each size and the number of parallel synchronous transfer in the best configuration, is discussed.
Differential output type microflow sensor
Authors: Esashi Masayoshi , Kawai Hiroshi , Yoshimi Kenichi 
Published: July 2007

AbstractTo realize a flow sensor sensitive to a flow rate lower than 0.1 cc/min, a differential output‐type mass‐flow sensor with a pair of heaters was fabricated using the micromachining technique. In a conventional sensor with a single heater, sensitivity degradation occurs because of the natural convection around the heater. On the other hand, in the sensor in this study, the influence of the convection was eliminated by utilizing the differential outputs between the pair of heaters which were located closely together. As a result, the nonlinearity of the sensor was less than 2 percent even when the flow was lower than 0.1 cc/min.
Autostereoscopic 3‐D television
Authors: Isono Haruo , Yasuda Minoru , Takemori Daisuke , Kanayama Hideyuki , Yamada Chihiko , Chiba Kazuo 
Published: July 2007

AbstractThis paper describes a diagonal autostereoscopic three‐dimensional (3‐D) television system with a liquid‐crystal video projector, the picture of which could be observed without the need to use special glasses. As the representation method of 3‐D images of this system, the pixels from four television cameras are composed electronically to make stripe images which are projected onto the rear surface of a lenticular screen by a high‐quality HDTV liquid‐crystal video projector. In this way, clear full‐color diagonal stereoscopic 50‐inch television pictures could be displayed.Besides the lack of obligation to use special glasses, the advantages of this system are: the observation range is broadened, compared to the previous stereoscopic 3‐D television; and the pictures are more natural and easier to observe. The newly realized diagonal autostereoscopic 3‐D television system, the lenticular screen, the diagonal autostereoscopic 3‐D cameras, the recording equipment of 3‐D pictures, etc., are discussed in this paper.
Effect of Ag2O on fishing effect of bipbsrcacuo superconductor
Authors: Lee Sangheon , Akiba Yukio , Kurosu Tateki , Iida Masamori 
Published: July 2007

AbstractIn this study, the fishing effect observed in a Bi‐based BiPbSrCaCuO (BPSCCO) superconductor was investigated. The electromagnetic properties of a silver‐oxide (Ag2O) doped BPSCCO superconductor and an undoped superconductor were evaluated to investigate the contribution of the pinning centers to the fishing effect.It was confirmed experimentally that a large amount of magnetic flux was trapped in the Ag2O doped sample than that in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence mechanism of the fishing effect.It is considered that by adding Ag2O, the area where normal conduction takes place increases and the magnetic flux penetrating through the sample increases. It also is considered that Ag2O acts to increase pinning centers of magnetic flux, contributing to the occurrence of the fishing effect. The occurrence mechanism of the fishing effect can be explained by a qualitative model based on the relationship between the pinning centers and the distribution of the lines of magnetic force caused by a toroidal permanent magnet.
Properties of bridge‐type weak‐link device with YBCO thin film
Authors: Park Chan‐Hoon , Kobayashi Tadayuki , Goto Toshinari 
Published: July 2007

AbstractThin films of YBaCuO were deposited onto polished MgO(100) substrates by a dc hollow cathode sputtering with stoichiometric YBa2Cu3Oz targets. The films of Tc zero with a good c‐axis orientation were fabricated successfully under the condition of a sputtering gas Ar + 5% o2, sputter‐pressure 820 m torr, and substrate temperature during deposition 700°C. The present study aims to realize a variable thickness bridge (VTB) device with thin bridge portions.VTB devices were fabricated by using photolithography, oblique incident evaporation of Al, and fine fabrication of 85 to 410 nm by low‐energy ion‐beam etching. Measurements were made for a frequency from microwave (9.67 GHz) to millimeter wave (94 GHz). Those devices were found to respond properly to a millimeter wave.
Switched branch line pin diode phase shifter
Authors: Matsunaga Makoto , Katagi Takashi , Hashimoto Tsutomu , Nakahara Shintaro 
Published: July 2007

AbstractAs a small phase shifter with a phase shift of 180 degrees from two PIN diodes, a switched branch‐line phase shifter is proposed and its characteristics, design method, and experimental results are presented. In the present phase shifter, the ratio of the characteristic impedances of the main line and the branch line is made to be 1 : 2. It is found that by this ratio the matching is always possible regardless of the impedance value of the diodes. The relationship is shown between the diode parameters and the circuit to obtain a phase shift of 180 degrees. In addition, the magnitude of the diode loss inherent to the present phase shifter is expressed in terms of the switching cutoff frequency which is a figure of merit of the diode. Also, the relationship is obtained between the input power and the voltage applied to the diode so that the maximum power capability determined from the breakdown voltage of the diode is obtained. Further, a phase shifter is fabricated atLband so that the effectiveness of the design method is confirmed.The performance of the phase shifter fabricated for experiment has a phase‐shift error of 7°MAX, an insertion loss of 0.5 dBMAX, VSWR of 1.4MAX, and maximum peak power of about 3 W in the PIN diode with a breakdown voltage of 60 V. These results agree well with the design values. The present phase shifter does not require hybrid couplers used in a reflection type and which occupy a large area. In addition, this phase shifter is useful for size reduction and cost reduction since only two diodes are needed.
A numerical analysis of plane‐wave diffraction from a multicoated grating
Authors: Matsuda Toyonori , Okuno Yoichi 
Published: July 2007

AbstractIn this paper, a numerical analysis algorithm has been derived for the analysis of the problem of plane wave diffraction by a multilayered grating. This algorithm is based on the Yasuura method with the smoothing procedure and can be applied to the problems of arbitrary multilayered dielectric (or metallic) grating with smoothly shaped grooves. The convergence of the approximate solution obtained by the present algorithm has been investigated numerically. It was demonstrated that a highly accurate approximate solution can be computed by the introduction of the smoothing procedure.The present algorithm is applicable to problems of a multilayered grating over the range from infrared to visible. As a numerical example, the diffraction efficiency of the multilayered diffraction grating made of alternate lamination of the high‐index and low‐index dielectric layers deposited on a metal grating is calculated by the algorithm in this paper.The following items are confirmed: (1) by coating dielectric films, the power absorption of the incident light by the metal grating is reduced in a specific wavelength region; and (2) in a multilayered grating, anomalous resonant absorption occurs by the coupling of the guided mode excited by the dielectric thin film and the diffracted wave.