bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and core loss of CoZrMo/polyimide stacked thin‐film core
Authors: Okuno Hikaru , Sakaki Yo 
Published: July 2007

AbstractA stacked thin‐film core for large amplitude rf magnetization is fabricated. The soft magnetization characteristic and loss is measured and the application of the core is discussed by comparing it with other types of cores. The core is formed by depositing a 2‐μm thick CoZrMo film on a 12.5‐μm thick polyimide film using an opposing target sputtering system. When the target ratio of Co:Zr:Mo was 82.2 percent:5.7 percent:12.1 percent, the saturation magnetic flux density Bs was 0.32 T. Even without thermal treatment, a core with a small coercive force (Hc) = 4.8 A/m (0.06 Oe)) is obtained.The hysteresis loss was close to that of a 5‐μm thick crystalline permalloy wound core but is one order of magnitude higher than that of amorphous (FeCoCr)75(SiB)25 thin‐film ribbon. This indicates that the core should be heat‐treated to improve the hysteresis property. When the maximum magnetic flux density Bm was 0.1 T at 10 MHz, the core loss was about 8 J/m3, which was close to that of 3.8‐μm thick amorphous (FeCoCr)75(SiB)25 thin‐film ribbon, which provides the lowest core loss.When Bm = 0.02 T at 10 MHz, the core loss was one‐third that of the supermalloy wound core and one‐tenth that of MnZn ferrite. At 4 MHz, the loss was lower than that of a 5.3‐μm amorphous (FeCoCr)75(SiB)25 thin‐film ribbon. The frequency dependence of the core loss was less than that of other cores because the eddy current loss was low.The proposed core can be applied for a high‐amplitude rf magnetization if the hysteresis loss is reduced.
An experimental study on the increasing phenomena of light intensity at the latter half of opening arc
Authors: Kubono Takayoshi , Okumura Takahiro 
Published: July 2007

AbstractThe time dependencies of the voltage, current, and the radiated light intensity of the opening arc discharge were investigated on butt‐type contacts where one end each of two silver columnar bars was fastened to a holder with large mass. Then electrical contacts were formed with the other end of the bar in the dc 10‐A resistive circuit.It was found that the light intensity increases suddenly at the latter half of an arc duration if the 1‐mmϕ electrode is long. However, if the 1‐mmϕ electrode was exposed with air‐blow or if the electrode diameter was 5 mm, the sudden increase in the light intensity was not observed at the end of the opening arc duration.When one end of a high‐temperature bar was heated further, the temperature gradient near the heated surface becomes smaller and the heat quantity flowing by thermal conduction is smaller. Therefore, the heated surface becomes further high temperature, thereby causing the acceleration of evaporation of the electrode material. We believe that at the latter half of a long opening arc duration, the number of atoms evaporated from the electrode increases, the number of ionized atoms increases, and then the light intensity increases suddenly.
Characteristics of an open‐boundary circular Čerenkov laser immersed in an infinite magnetostatic field
Authors: Horinouchi Katsuhiko , Hirakawa Isao , Shiozawa Toshiyuki 
Published: July 2007

AbstractA theoretical discussion is given on the characteristics of an open‐boundary Čerenkov laser which is composed of a circular conducting cylinder coated with a dielectric sleeve and a hollow relativistic electron beam focused with infinite magnetostatic field, and the following results are obtained.First, the growth rate decreases as the dielectric‐beam gap increases. Second, the frequency of the growing wave can be varied by varying the velocity of the electron beam. Third, compared with the case for a nonmagnetized beam, the growth rate decreases for an infinitely magnetized beam; but otherwise similar characteristics are obtained for both cases. Finally, as the ratio of the radius of a conducting cylinder to the thickness of a dielectric sleeve increases, the growth rate and frequency of the growing wave increase gradually and they tend to the characteristics for a planar laser for sufficiently large values of the ratio.
Surface‐emitting semiconductor lasers and surface‐operating functional devices
Authors: Iga Kenichi 
Published: July 2007

AbstractSurface‐emitting semiconductor lasers have attracted attention because of their applications in new fields of optoelectronics such as parallel processing, optical interconnections, etc. In these lasers, light is emitted perpendicularly to the semiconductor substrate which creates the possibility of two‐dimensional parallel integration.In this paper, the state of research on surfaceemitting semiconductor lasers is discussed first as are various structures of surface‐emitting semiconductor lasers with vertical, horizontal, and folded resonators. The formation of a buried structure or highly reflective configuration employed to achieve the low threshold operation of surface‐emitting semiconductor lasers with vertical cavities are focused upon and their oscillation characteristics of two‐dimensional array arrangements are introduced.Finally, the recent progress of surface‐emitting lasers and surface‐operating functional devices together with their future prospects are presented.
A new method of optical coupling between waveguides and photodiodes using waveguide‐type layered optical couplers
Authors: Koike Shinji , Takahara Hideyuki , Katsura Kohsuke 
Published: July 2007

AbstractIn an attempt to develop a waveguide‐type layered optical coupler which has the same cross‐section dimension of dielectric layers as the optical waveguide, a new optical coupling system is discussed. This system is designed to couple the flip‐chip‐mounted photodiode with the waveguide. Because the proposed couplers can be manufactured in quantity, they have the potentiality for applying to optical interconnection modules where a large‐scale and a large number of optical connections are required.The present paper discusses the performance of the waveguide‐type layered optical coupler based on the analysis by the beam propagation method (BPM) and on the experimental results. Both the power transfer from the waveguide to the coupler and the radiation process from the coupler to the photodiode are both clarified. These results indicate the optical coupling between the photodiode and the optical waveguide. Further, the optimum coupler‐structure for the maximum power transfer ratio from the waveguide to the coupler, which performance is least sensitive to the thickness error, is discussed. The coupling efficiency of 22 percent for the Gediode is obtained.
Analysis of an optoelectronic integrated functional device with positive optical feedback
Authors: Osawa Yasuhiro , Onodera Noriaki , Satoh Shiro 
Published: July 2007

AbstractA fundamental and analytical model on optoelectronic integrated functional devices is discussed. In this model, the optoelectronic device with the positive feedback consists of the light emitter and the photodetector, which are electrically connected in series. The positive optical feedback is considered from the light emitter to the photodetector. A steady‐state solution is discussed for the optical functions of the device for various parameters. The light emitter is treated as the current‐light transducer, and the photodetector is modeled as the resistance which varies with the input‐light intensity. The parameters of voltage V, load resistance RL, light feedback ratio β, and conversion efficiency A are introduced. For those parameters, the condition for each optical function of the device is solved. The two cases for the detector characteristics are discussed and the distribution map of functions is obtained. Also, the parameter fitting is made to compare with the experimental results obtained for the hybrid structure and a reasonable agreement is achieved.
Propagation of nonlinear surface wave in linear‐nonlinear optical waveguide structure
Authors: Ohke Shigeaki , Umeda Tokuo , Cho Yoshio 
Published: July 2007

AbstractIn a nonlinear optical waveguide, it is not necessary to use a three‐layered structure as in the case of a linear optical waveguide. Even in a two‐layered structure of linear‐nonlinear configuration, there exists a stable light propagation mode along the interface. It is possible to study the structure by subdividing the nonlinear medium constituting one side of the two‐layer configuration.This paper studies the behavior of the nonlinear surface propagation wave along the interface of the two‐layered linear‐nonlinear configuration by a numerical solution based on the multisegmentation method for the case where the optical intensity dependence of the nonlinear refractive index of the nonlinear region is positive. There also exists a stable light propagation mode in a linear‐nonlinear multilayered optical waveguide in which the nonlinear medium on one of the two regions is made of a multilayered configuration such as a multiple quantum well. It is shown that this linear‐nonlinear multilayered optical waveguide can be treated globally as a linear‐nonlinear two‐layered structure because the nonlinear multilayered region can be treated as a single‐layered nonlinear medium. Further, it is demonstrated that the behavior of the nonlinear surface wave in a nonlinearlinear‐nonlinear three‐layered structure can also be studied in a manner similar to that for the linear‐nonlinear two‐layered structure.
Surface potential control of electrostatic recording apparatus using a drum on which a photoconductor sheet is wrapped
Authors: Umeda Takao , Nakazawa Takasi , Miyasaka Tooru 
Published: July 2007

AbstractThis paper discusses the surface potential control of a high‐speed electrostatic recording apparatus using a drum wrapped with a photoconductor sheet. In the conventional surface potential control, the absolute value of the surface potential on the photoconductor is detected by a surface potential sensor to control the grid voltage. Therefore, in this method, the potential control is strongly dependent on the accuracy of the surface potential sensor and the sensor must be calibrated periodically.In the method proposed herein, the surface potential of the sealing (cap) section where the photoconductor sheet is pulled out is set at the standard charge potential and the grid voltage is controlled by equalizing the surface potentials on the cap and the photoconductor.After evaluating the application of our method to a high‐speed printer which is capable of printing at speeds over 100 pages/min, it was found that the surface potential on the photoconductor can be maintained at 700 ± 15 V.Since the control method herein is a relative comparison method, the system performance is not influenced by the voltage drift caused by the toner adhered to the sensors. Therefore, the calibration of the surface potential sensor is not necessarily required. In addition, since relative output low‐cost surface potential sensors can be used, the control system can be cheaper.
Selective erasable and programmable NAND‐type MNOS memory
Authors: Sato Kazuo , Ueda Kenji , Kojima Makoto , Takata Takashi , Yokozawa Kenji , Morita Michio , Onishi Hideaki 
Published: July 2007

AbstractThis study was made of a new programming method and memory characteristics of an NAND‐type MNOS memory cell which uses half the size of the conventional two‐transistor structure using the same design rule. As a result, it was found that inadvertent writing can be prevented under the write inhibit mode by using a new sequencing (PURGE mode) which moves unnecessary thermal electrons generated under MNOS gate to the bit lines.Also, it was verified that selective rewriting by NAND type can be realized. This prototype of NAND‐type MNOS memory cell can realize PURGE effect by applying 3 V and a very short pulse of 30 ns. It was found out also that possible number of PURGES of unselected memory cells at each writing is about 1010. The limit of the read cycle is about 106when the word line consists of 128 bytes.
Application of a liquid crystal microlens to an optical fiber switch
Authors: Nose Toshiaki , Sato Susumu 
Published: July 2007

AbstractAn optical fiber switch has been fabricated by combining an optical fiber and various liquid crystal microlenses prepared by using different liquid crystal materials and molecular orientation methods. By adopting various driving methods, the improvement in response and recovery characteristics has been attempted. In hybrid‐aligned liquid crystal microlens using a liquid crystal with positive (p‐type) dielectric anisotropy, good focusing characteristics can be obtained and a wide variability has been attained because there are no disclination lines which normally occur in the homogeneously aligned liquid crystal microlens. In hybrid‐aligned liquid crystal microlens using a liquid crystal with negative (n‐type) dielectric anisotropy, the improvement in focusing characteristics compared to the homeotropic molecular orientation has been attained because the polarization characteristics of incident light can be used effectively. It has also been clarified that the recovery characteristics are improved by the dual frequency driving method and that the response and recovery characteristics in the case of microlens with n‐type liquid crystal are both improved by the driving method with bias voltage application, which are also effective for the variable characteristics of the coupled light. Furthermore, these characteristic differences are discussed in terms of the liquid crystal molecular orientation state in the nonuniform electric field for each liquid crystal microlens.
An optoelectronic adaptive device and its learning performances
Authors: Kanamori Kohji , Tsuji Kiyotaka , Yonezu Hiroo , Pak Kangsa , Takano Yasushi 
Published: July 2007

AbstractTo realize a large‐scale and high‐speed neural network, an exclusive hardware is indispensable, as is a new concept on a circuit with an enormous number of interconnections among neurons. An important function in neurocomputing is self‐organization by learning. This self‐organization can be accomplished by the adaptive function of the synaptic connection in neurons, but no such devices have been realized. Based on the optoelectronic‐integrated circuit (OEIC) model with optical wiring using the parallelism of light, a new device/circuit has been designed and fabricated. This device has the adaptive function in which a synaptic connection weight Tij changes with an external pulse (teaching signal). The performance of the device which consists of fundamental networks based on back propagation (BP) was examined and compared with the simulation result. The basic adaptive function and self‐organization function were confirmed.
Vertical‐to‐surface transmission electrophotonic device and its application to optical interconnection
Authors: Yamanaka Yutaka , Numai Takahiro , Yoshihara Kazuhiro , Kosaka Hideo , Kurihara Kaori , Sugimoto Mitsunori , Kasahara Kenichi , Ogura Ichiro , Kubota Keiichi 
Published: July 2007

AbstractIn optical interconnection, the cascade optical interconnection using two‐dimensional optical switch devices is an important basic structure. To realize such an optical interconnection, the vertical‐to‐surface transmission electrophotonic device (VSTEP), which has a planar structure easy for two‐dimensional integration and is capable of light emission, light detection, and latching, has been developed.Utilizing the optimized combination of a pnpn thyristor structure, double heterojunction structure and vertical cavity structure, efficient laser mode emission and switching characteristics were obtained.In the optical interconnection using the differential structure, optical switching was achieved with optical energy as low as 150 fJ. An operating speed of 25 MHz was confirmed in the continuous mode. In addition, using the cascade characteristic in the device‐to‐device interconnection, the shift‐register operation was carried out using the optical interconnection between four optical array switches.
Amplitude‐stabilizing circuits for three‐phase ultralow‐frequency oscillator
Authors: Miyazaki Tomoyuki , Takeishi Taisuke 
Published: July 2007

AbstractThe rise time of the oscillation amplitude which is a problem in an ultralow‐frequency oscillator is discussed for a three‐phase CR oscillator. Four amplitude‐stabilizing circuits are proposed and their dynamic characteristics are compared by simulations. The computation was based on the Runge‐Kutta method. The analysis was applied to the three‐phase ultralow‐frequency switched‐capacitor oscillator to confirm the operation.By means of the method for installing a positive feedback in each of the three‐phase shifters, a rise time of less than one‐tenth period was obtained. Analog multipliers were used for the control of the feedback voltage gain and the oscillation amplitude detection.
Effects of air pressure on transition boundary from metallic to gaseous phase in W break arc
Authors: Yoshida Kiyoshi , Takahashi Atsuo 
Published: July 2007

AbstractTo determine whether aW break arc continues only in the metallic phase until its extinction or its phase changes from the metallic phase to gaseous phase, the air pressure P was varied from 50 to 760 mmHg under the condition where the supply voltage E was 48 V, the load inductance L was 2.3 mH and the close contact current I was between 0.6 and 6 A.The waveforms of arc with a phase other than the metallic phase were categorized as types I and II. In type I, the voltage increased rapidly in a stepped form and reached 30 to 40 V in low pressure. In type II, the gradient of the voltage increased varied. Type I occurred at a lower I0 than type II. In type I, I0 decreased with a decrease of P while in type II I0 increased with a decrease of P. When I0 was close to the threshold value of type II, the metallic phase duration tm increased suddenly.The contact gap corresponding to the sudden increase in the metallic phase duration agreed with the minimum point of Paschen's spark discharge curve under a given pressure.
A velocity‐matched guided‐wave optical modulator using an inverted slot line
Authors: Yoneyama Tsukasa , Niinuma Keiichi , Kanno Seiji 
Published: July 2007

AbstractWith the purpose of developing a highly efficient guided‐wave optical modulator, an inverted slot line has been proposed for realizing a perfect velocity matching. Modulation experiments were conducted at the 10‐GHz band. Despite its simple structure, the inverted slot line can increase the phase velocity of the modulating wave substantially by changing the spacing between the slot surface and the ground plane, and hence the velocity matching can easily be attained. From the structural limitation of the inverted slot line, the input of the modulating wave from a coaxial cable must rely on the non‐contact excitation.A transition for such a purpose was fabricated first. Next, the propagation characteristics of the inverted slot line were investigated experimentally. It was confirmed that perfect velocity matching can be realized between the optical wave and the modulating wave if the spacing between the slot surface and the ground plane is about 200 μm for 10 GHz and 22 μm for 50 GHz, although certain variations exist, depending on the slot width. An optical modulator was actually built with a Ti:LiNbO3 optical waveguide, and the phase modulation operation was confirmed at a wavelength of 633 nm. At the modulating frequency of 9 to 12 GHz, the maximum phase modulation of 2.11 rad was measured with a modulating power of 100 mW. Hence, the possibility of a highly efficient guided‐wave optical modulator was demonstrated.
Finite‐element analysis of open‐type axially symmetric waveguides
Authors: Ohkubo Fuminori , Maruta Akihiro , Matsuhara Masanori 
Published: July 2007

AbstractA new method is proposed for the numerical analysis of the propagation characteristics of open‐type axially symmetric waveguides by means of the finite element method.First, a novel variational expression suitable for the waveguide analysis is presented which uses electric field components as the trial function. When this variational expression is used in the finite element analysis, no spurious solution is generated.Next, a mapping technique is proposed to apply the finite element method to the entire region of the opentype axially symmetric waveguide. In this method, the entire region of the open‐type axially symmetric waveguide is divided into a finite core region and an infinite cladding region. By means of a coordinate transformation, the cladding region is mapped to a finite region. The finite element method is applied to the finite core and mapped cladding regions and the variational expression is reduced to a generalized eigenvalue problem in which the propagation constant is the eigenvalue. Hence, no repetitive calculation is necessary and the computational effort can be reduced.As practical examples, a step index fiber and a graded index fiber are analyzed numerically and the validity of the proposed method is confirmed.
LiNbO3 waveguide SHG devices based on a ferroelectric domain‐inverted grating induced by SiO2cladding
Authors: Fujimura Masatoshi , Suhara Toshiaki , Nishihara Hiroshi 
Published: July 2007

AbstractLiNbO3 waveguide quasi‐phase matching (QPM) second‐harmonic generation (SHG) device is promising as a short‐wavelength coherent light source. To realize such device it is important to establish a ferroelectricdomain inversion technique. The authors have found that by heating an LiNbO3 crystal for two hours at 1000°C with SiO2 cladding of about 0.1 μm thick on the +Z surface, the domain inversion is induced under the cladding. This inversion method is suitable for device fabrication since uniform domain inversion is induced with good reproducibility under a wide heat‐treatment condition. The dependence of the SHG efficiency on the waveguide size and on the domain inversion cross‐section structure is calculated.A prototype waveguide SHG device, which can compensate for the residual phase mismatch, with domain‐inverted grating formed by this inversion method was demonstrated. An SHG experiment using a CW‐Nd:YAG laser light as the fundamental wave resulted in a high SHG efficiency of about 45‐percent W. It was seen that the domain‐inverted grating formed by the present method is suitable for application to QPM‐SHG devices.
Hybrid‐type optical bistability in a thin‐film polymer waveguide doped with nonlinear organic dyes
Authors: Muto Shinzo , Miyagawa Koichi , Ozawa Toshio , Sugiyama Shigeru 
Published: July 2007

AbstractIt is demonstrated theoretically and experimentally that hybrid‐type bistability operations based on the Kerr effect can be obtained in a Mach‐Zehnder interferometer‐type thin‐film optical waveguide made of a polymer thin film doped with nonlinear organic dyes such as disperse orange 3, trans‐β‐carotene and nitroaniline derivatives. It is shown also that the Kerr constants of the dye‐doped polymer thin film can be measured by using the optical control characteristics in this device. The values are 10−14 to 10−13 m/V2 even with dye‐doping of several wt%. Further, an optical‐optical switching operation is possible although a high feedback gain is required.