bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid optical bistability in ferroelectric liquid crystal and its dynamic characteristics
Authors: Tagawa Akira , Moritake Hiroshi , Ozaki Masanori , Yoshino Katsumi 
Published: July 2007

AbstractIn the area of optical logic and optical information processing, such nonlinear optical devices as optical Instability, optical amplifier, and optical limiter are important basic elements.In this paper, the hybrid optical bistability and optical limiter characteristics are realized by means of an electrical linear feedback to a ferroelectric liquid crystal cell (SSFLC cell). If the feedback gain is positive, the optical bistability is obtained while the optical limiter characteristics are obtained if the gain is negative. Also, it was demonstrated that by instantaneously increasing or cutting the incident optical intensity in a pulsed state in the optical bistability region, the transmission light intensity can be switched from the low‐transmission state to the high‐transmission state or from the high‐ to low‐transmission state. The minimum pulsewidth needed for switching is 70 μs for the low‐transmission state to the high‐transmission state and 50 μs for the high‐transmission state to the low‐transmission state. Since the speed is very fast, the high‐speed response of the ferroelectric liquid crystal is used effectively.
Development of a scanning‐type mie‐lidar system for global measurement of aerosol density in the atmosphere
Authors: Saito Yasunori , Iijima Ken , Kobayashi Fumitoshi , Nomura Akio , Kano Tetsuo 
Published: July 2007

AbstractTo understand the dynamic behavior of the aerosol density in the atmosphere, a Mie scattering lidar was fabricated. The system consisting of a YAG laser and a receiving telescope is scattered automatically in the horizontal direction with a stepping motor and enabled a global real time monitoring over a radius of 5 km. The measured results are displayed in an image as a global mapping chart of the aerosol density in the atmosphere. From the end of November 1989 to the present, steady measurement has been carried out twice a week. Interesting results have been obtained including the existence of a high concentration aerosol region along a major highway.
Instabilities and Their Characterization in Mach‐Zehnder Ti:LiNbO3 Optical Modulators
Authors: Jumonji Hiromichi , Nozawa Toshinori 
Published: July 2007

AbstractFor the Ti‐diffused LiNbO3 optical modulator, which is expected to be applied to optical communication systems and optical measurement instruments, quantization of various unstable phenomena degrading the practical operations is attempted. The characteristic parameters related to each phenomenon and their temperature dependence were measured under the condition of a constant optical output. The following observations were made:

(1) The polarity and the relaxation time of the short‐term dc drift (namely, the variation of the driving point immediately after the application of the dc bias) depend on the configuration of the buffer layer;
(2) The temperature drift (namely, the variation of the driving point due to that of the ambient temperature) is a short‐term drift phenomenon and its relaxation time is related to that of the short term dc drift;
(3) The long‐term dc drift (namely, the variation of the driving point over a long time) depends on the magnitude and polarity of the electric field applied on the waveguide region. Its relaxation time is much larger than those of other phenomena; and
(4) From the temperature dependence of the relaxation time of each phenomenon, it is found that their activation energies are almost equal and are about 0.7 eV.
Further, based on the equivalent circuit model newly proposed, the relationship among the parameters was evaluated. It is found that each unstable phenomenon can be explained by the equivalent circuit model in which the formation of the space charge layer is taken into account.
Three‐dimensional full‐wave analysis with nonlinearity and line characteristics of device by electromagnetic field analysis on time domain
Authors: Kimura Hideaki , Yoshida Norinobu 
Published: July 2007

AbstractRecently, with the increased bandwidth and operating frequencies in the integrated circuits, the nature of the wave has begun to appear in the signals in the ICs. Therefore, it has become indispensable to use distributed circuit treatment of the circuits such as the propagation delay. Also, in the design of the circuit for a broadband and large signal operation, an analysis method is required in which both the distributed devices and the nonlinear devices are analyzed in a unified manner. A simple method for introducing the distributed effect in the nonlinear circuit analysis is to construct the interconnect with an LC ladder network and to carry out the calculation in the time domain. It is difficult to introduce the frequency dispersions of the transmission line.On the other hand, the three‐dimensional full‐wave analysis is effective in the sense that the frequency dispersion due to the circuit configurations is taken into account automatically. Also, recently, the harmonic balance method has been introduced in which the nonlinear circuit analysis is conducted by separating the nonlinear and linear parts of the circuit. However, the number of harmonics to be considered is limited.In this paper, with a view to circuit analysis containing the nonlinear devices and the distributed effect in the interconnect, nonlinear devices are included in the three‐dimensional time‐domain analysis methods such as the FD‐TD and spatial network methods. A systematic three‐dimensional full‐wave analysis is realized for the large signal operation of the circuit containing nonlinear devices.
Design of a thermal print head for high‐speed and high‐resolution printing
Authors: Shibata Susumu , Kanamori Takashi 
Published: July 2007

AbstractThermal analysis of a thin‐film thermal print head was carried out with the aim of obtaining guidelines for the design of a print head for high‐speed and high‐resolution printing.The analysis showed that if current is passed through the heating resistors for a short period, there will be a time lag between the temperature increase in the resistors and the temperature increase in the heat sensitive paper. Furthermore, although a short pulse is preferable for high‐resolution printing, there is a point beyond which further decrease in the duration of the pulse has little effect.It was estimated that changes to the heat insulation layer and protective film alone would not lead to an improvement in the performance of the print head as a whole. The printing test yielded the same results as those provided by the thermal analysis. For example, a pulse duration of 5 ms is not preferable for a resolution of 16 dots/mm. However, the contrast obtained with a pulse duration of 0.3 ms may also be obtained with a pulse duration of 0.8 ms.
Resolving power of infrared upconverter‐spectrometer using rotation of a medium with periodic variation of nonlinear coefficients
Authors: Koyanagi Kojiro 
Published: July 2007

AbstractAs an application to the upconverter which converts infrared light to visible light by means of a three‐wave sum frequency conversion, an infrared upconverter‐spectrometer is proposed which uses rotating scanning of a periodic nonlinear medium (consisting of layers of media with the sign of nonlinear optical coefficient alternately inverted). In this structure, the wavelength selection capability of the phase matching in the parametric interaction is used. The resolving power and the maximum output (conversion efficiency), which are important basic characteristics in the infrared upconverter‐spectrometer, are studied theoretically. The resolving power versus the incident angle of the pumping light is studied in detail with the medium dispersion and the two‐dimensional size taken into account.As examples, the infrared upconverter‐spectrometers for 10‐ and 3‐μm bands using GaAs and LiNbO3 as the periodic nonlinear media have been considered and their resolving power has been derived numerically. Excellent visible detectors can be used in these infrared spectrometers. In addition, they can use isotropic media with ordinary dispersion and large nonlinear optical coefficients. By means of rotating scanning of the crystal, they can have high sensitivity and high response time. Depending on the direction of incidence of the pumping light, a resolving power higher than that of conventional structures can be obtained.
Automatic synthesis of holographic stereograms with ray‐traced image data
Authors: Kinoshita Kenji 
Published: July 2007

AbstractAn automatic synthesizing method of holographic stereograms (HSs) has been studied for computer‐graphic images, and experimental results of image reconstruction have been presented. In the synthesis of the HSs, raytraced image data of 180 frames were generated, changing a viewpoint. Then these data were recorded on a holographic film of about 70 mm x 300 mm using a liquid crystal television panel as a spatial light modulator. The fabrication time of one HS was about 50 min. In image reconstruction with a 5‐mW He‐Ne laser, it has been possible to display three‐dimensional images which have a good parallax effect.
The I‐V characteristics of polycrystalline silicon diodes and the energy distribution of traps in grain boundaries
Authors: Yamamoto Ichiro , Takeda Ryo , Suzuki Yoshihisa , Kuwano Hiroshi , Saito Yoji 
Published: July 2007

AbstractThe current‐voltage characteristics of p+pn+ structure polycrystalline silicon diodes and the energy distribution of traps in the grain boundaries are measured before and after plasma hydrogenation. Plasma hydrogenation increases the forward current and reduces the reverse current. The energy distribution of nonhydrogenated film has a peak around the midgap; this peak disappears after hydrogenation. The change in diode current produced by plasma hydrogenation can be explained by this difference in the energy distribution of the traps.
Characterizations and growth mechanisms of the surface‐oxidized layer formed on Al‐Nb‐(N) alloy films
Authors: Noya Atsushi , Sasaki Katsutaka 
Published: July 2007

AbstractThe oxide growth and the characterization of a thin protective layer peculiar to an aluminum surface have been examined by varying the composition of Al‐Nb alloy films and by nitrogen doping. At room temperature, an aluminum oxide layer was formed on an Al‐Nb alloy surface by preferential oxidation. In the Al‐Nb alloy with an Al‐rich composition, Nb underneath the oxide layer was not oxidized, while in the alloy with an Nb‐rich composition, oxidized Nb was present on the oxidized surface layer even at room temperature and the oxidized layer grew as the temperature increased.The lower oxides of Nb which were already present at room temperature enhance the oxidation of Al, causing a decrease of the activation energy for oxidation. As a result, the oxidized layer grows as the temperature increases. To confirm the presence of activation process of Al oxidations by impurity doping, an Al‐rich alloy was doped with nitrogen. The result shows that a similar activation process accelerates the oxide growth by nitrogen doping. It was then concluded that the possible activation process of the Al cations is involved in the mechanism of losing the protectivity in the Al oxide.
Wafer‐to‐wafer temperature distribution control in a diffusion furnace
Authors: Matsuba Ikuo , Mokuya Kinji , Matsumoto Kuniaki , Yoshinaka Akira 
Published: July 2007

AbstractA control scheme to achieve wafer‐to‐wafer temperature uniformity in the reaction tube used for oxidation, diffusion, or annealing during semiconductor processes is proposed. In the analytical model, self‐radiation loss, radiation between neighboring wafers, radiation from the tube wall, and thermal diffusion on a wafer surface are taken into account. The temperature monitoring points were the inlet, middle, and outlet of the reaction tube.The analysis indicates that if the tube wall temperatures at the inlet and outlet are 6 percent higher than that at the center of the tube, the wafer‐to‐wafer temperature becomes uniform. In the experiment, taking the silica tube temperature as the tube wall temperature, the increase in the temperatures at the inlet and outlet must be 5.6 percent to achieve wafer‐to‐wafer temperature uniformity, while it should be 6.9 percent if the temperature of the secondary tube is considered to be the tube wall temperature.Experiment results verify the effectiveness of the model. At the same time, the tube wall temperature is assumed to be influenced not only by the temperature of the silica tube but also by that of the secondary tube. The model predicts that the wafer temperature increased by 1°C if the tube wall temperature is increased as described in the foregoing. However, in the experiment, the wafer temperature increases by 1.6°C at most.
Photochemical vapor‐deposited silicon oxynitride films for solar cells
Authors: Shibata Noboru 
Published: July 2007

AbstractSilicon oxynitride films (SiNXOY) were deposited at deposition temperatures between 100 and 300°C using mercury‐sensitized photochemical vapor deposition. The light source was a low‐pressure mercury lamp and the source gas was a mixture of NH3 gas and 5 percent SiH4 gas (95 percent N2 gas). The quality and interface property of these films were better than those of plasma‐CVD films. However, in the former films, the film quality was unstable and degraded rapidly with time when the deposition temperature was low.Electron spectroscopy for chemical analysis (ESCA) indicated that the invasion of oxygen from air to the film caused a change in the film composition, resulting in the degradation of film property with time. The photochemical vapor deposition and plasma‐vapor deposition SiNXOY films were used as an antireflective coating for a single‐crystal‐Si solar cell; and it was found that using the former films, the short‐circuit current density and effective conversion efficiency were higher than by using the latter films. The difference in the foregoing results was believed to be due to the improvement of the interface property by photochemical deposition films.
Implementation of a class of asymmetrical neural networks with application to an a‐d converter
Authors: Sato Shigeo , Nishimura Toshihiko , Murota Junichi , Nakajima Koji , Sawada Yasuji 
Published: July 2007

AbstractThis paper attempts to clarify the problems which occur in implementation of a large‐scale neural network. First, a neural A‐D converter with CMOS circuits is designed. Asymmetrical synaptic weights were used to avoid the local minima problem for a neural A‐D converter. Furthermore, a chip is fabricated using 4 μm CMOS technology. Its successful action as an A‐D converter is verified and some possible causes of misoperation of the present circuit are presented.
Optical soliton transmission
Authors: Nakazawa Masataka 
Published: July 2007

AbstractThis paper discusses the basic properties and advantages of optical solitons which are under investigation in many countries for the purpose of their application in realizing ultrahigh‐speed communications. Especially, the recent developments in erbium optical amplifiers, which are epochal in optical soliton transmission, have made soliton communication actually realizable. Here, the techniques of the so‐called dynamic soliton communication are considered and recent research is reported.
Substrate‐voltage control circuits for DRAMs at power‐on timing
Authors: Miyamoto Hiroshi , Suwa Makoto , Tokami Kenji , Yamada Michihiro 
Published: July 2007

AbstractThis paper proposes two substrate voltage control circuits to prevent the latch‐up at power‐on of CMOS DRAM due to the substrate potential rise.One of the circuits is a substrate voltage‐clamp type which clamps the substrate voltage to the ground during power‐on to prevent the substrate potential rise due to the capacitive coupling from then‐well.The second circuit is a clamping circuit of memory cell‐plate voltage and bit‐line precharge voltage to the ground also at power‐on to prevent the substrate voltage rise due to the capacitive coupling from the memory cell plate and the bit line.The clamping period of these circuits is determined by the power‐on reset signals generated inside the DRAM chip during power‐on. Furthermore, to effectively operate the clamping circuits by different timing for clamp release of each clamping circuit, two‐step power on reset signals is used. Adopting these circuits to an actual 4‐Mbit DRAM test device, the desirable operation of the circuits by clamping the substrate voltage, the memory cell plate voltage, and bit‐line precharge voltage to the ground during power‐on has been confirmed by waveform observation. Then the latch‐up prevention during power‐on is confirmed in the actual device.
US‐DMOS: A novel structure for power mosfets
Authors: Morikawa Masatoshi , Yoshida Isao , Kobayashi Masayoshi , Fukuda Takashi , Fujita Yuzuru 
Published: July 2007

AbstractThis paper describes a novel vertical power MOS‐FET with low on‐resistance and large avalanche current, called US‐DMOS (U‐grooved self‐aligned DMOS). It features a U‐grooved self‐aligned source and base contacts with respect to the gate electrode, which reduces the cell size to two‐thirds the conventional cell size and reduces the parasitic base resistance.Using three‐dimensional simulation on this device structure, the reduction on the on‐resistance by the formation of the U‐groove and the increase of the avalanche current by the reduction of the base resistance were proved. In ann‐channel test device with a drain current of 60 V, the on‐resistance was 156 m Ωmm2, which is 30 percent lower than in a comparable device with a conventional structure. In addition, the avalanche current was one order of magnitude higher in this device.
Formulas for estimating the wide‐band reflection characteristics of inductive window with thickness in rectangular waveguide
Authors: Ishihara Fujiio , Sibazaki Toshihiko , Suga Takashi , Iiguchi Shinichi 
Published: July 2007

AbstractThe symmetric and nonsymmetric inductive windows in a rectangular waveguide are analyzed in a theoretically rigorous manner in which the window is treated not as a discontinuous but continuous structure and the normal mode expansion method (transmission line equation) is applied. The reflection coefficient including the phase is derived and a design chart applicable to windows with various dimensions is created. The analysis is carried out even for the cases in which the thickness of the plate cannot be neglected.Next, experiments are carried out at × band. It is confirmed that the theoretical and experimental results agree well in a wide frequency range even for the case with a nonnegligible plate thickness. Further, an equation with a better approximation than the one in the conventional approximation equation is derived for convenience of the circuit designer.
Propagating beam analysis by alternating‐direction implicit finite‐difference method
Authors: Yamauchi Junji , Ando Takashi , Nakano Hisamatsu 
Published: July 2007

AbstractThe three‐dimensional beam propagation problem expressed by the Fresnel equation is analyzed by the beam‐propagation method using an alternating‐direction implicit finite‐difference method (ADI‐BPM). First, following the formulation of the finite‐difference method, the equations to be analyzed are rearranged. The fundamental and higher‐order mode propagation problems in a step index fiber are treated, and the accuracy and advantages of the ADI‐BPM are investigated. It is found that the computing time is shorter and the step length in the propagation direction can be made larger in the ADI‐BPM than in the beam‐propagation method based on the fast Fourier transform (FFT‐BPM).As another advantage in the ADI‐BPM, the usefulness of the transparent boundary condition is described. It is shown that the spreading problem of a Gaussian beam can be analyzed without setting up the absorbing functions needed in the FFT‐BPM. Further, as an example to prove the effectiveness of the ADI‐BPM for the analysis of the problem in which the guided mode and the radiation mode are mixed, the transmission efficiency is evaluated in the case where an axial offset exists in the fiber junctions. The effect of the coherent coupling is studied.
Resonant frequency analysis of a dielectric ring resonator for a new method of moisture content measurements
Authors: Okamura Seichi , Sone Masahiro 
Published: July 2007

AbstractIt is proposed that the moisture content measurement for small and randomly shaped materials that was difficult by the conventional electrical methods be done by a new technique making use of the resonant frequency of a dielectric ring resonator. An analysis of the resonant frequency and a possibility of the new measurement method are discussed.First, for taking the correlation of the moisture content with the shift of the resonant frequency of a moist sample within a resonator caused by the change of the permittivity, the theoretical value of the resonant frequency was derived by the mode matching method when an arbitrary dielectric sample was placed at the hollow central part of a dielectric ring.A theoretical equation was derived and its validity was confirmed by comparison of the theoretical and experimental values for a known dielectric sample. From the relationship between the shift of the resonant frequency and the permittivity of the sample obtained from the theoretical equation, the shift of the resonant frequency is found usable for measurement of moisture content.Further, this was confirmed by the measurement in the case where cardboard is used as a sample in a Teflon ring resonator. The measured and theoretical results for high moisture contents were compared. The discrepancy from the theoretical results is several percent. A possibility was demonstrated for a new moisture content measurement technique based on the shift of the resonant frequency of a dielectric ring resonator and the sample weight.
Effect of conductor losses in new‐structure filters for suppressing microwave leakage
Authors: Iwabuchi Koji , Kubota Tetsuo , Sugaya Yukitoshi , Kashiwa Tatsuya , Fukai Ichiro 
Published: July 2007

AbstractAs a waveguide‐type broadband elimination filter preventing leakage from a microwave heating system, a waffle‐iron type filter is known which consists of a periodic structure of a multiple post structure with many circular or rectangular cylindrical metal posts placed periodically inside a waveguide. The theoretical analysis of this filter has been limited to the case in which the conductor loss is neglected. Therefore, the attenuation at the resonant frequency of this filter becomes infinite in the computation and is significantly different from the practical situation.To resolve this problem, the present paper derives theoretical equations including the conductor loss from the equivalent circuits for not only this filter but also the multiple‐slit type and the multiple rectangular‐plate type which are newly developed for mass production. The theoretical and experimental values are compared. It is confirmed that the frequency characteristics of the attenuation of the filter can be estimated theoretically including the resonant point.