bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of three‐dimensional shape and section of object on turntable by position‐sensitive device
Authors: Nakashima Wataru , Nagamura Eiji , Aida Teizo 
Published: July 2007

AbstractThis paper considers an object moving on a belt‐conveyor or on a turntable, and describes a system which measures with a high speed its shape and the cross section in horizontal and vertical directions. In the measurement, the object is scanned with a high speed by He‐Ne spotlight through a high‐speed rotating mirror with 10 mirror‐faces. The object is placed on a turntable and rotated 360 deg by a stepping motor. The two‐dimensional information of the scanned point is acquired by PSD. The operation is performed in synchronization to the scanning by a personal computer, and the cylindrical coordinates (r, z, θ) of 4800 points on the object are determined with as high a speed as 980 ms (200 μs per coordinate). A feature of this study is that the speed is improved by combining a high‐speed rotating mirror and a high‐speed PSD. Another feature is that the reference table for coordinate determination is stored so that the speed of the computation can be improved. At present, approximately 3 min is required by BASIC to display the coordinates, but the cross section can be displayed in 0.4 s using the machine language.
Design and fabrication of GaAs hall IC with SCFL Schmitt Trigger
Authors: Itakura Keijiro , Asada Hiroaki , Ueda Daisuke , Takagi Hiromitsu 
Published: July 2007

AbstractA GaAs monolithic Hall IC with superior temperature characteristics has been designed and fabricated by taking advantage of such GaAs material properties as large bandgap and high electron mobility. This IC is designed with SCFL circuits, operates with only a 5‐V power supply, and switches ON and OFF depending on the magnetic field intensity. In addition, it contains a Schmitt trigger circuit to prevent a malfunction by magnetic noise. As a result of designing for low power consumption, the power/current of the IC is approximately 17 mW/3 mA. According to the measurement, the magnetoelectric conversion characteristics and the power consumption of the IC do not show a noticeable change even at the ambient temperature of 150°C.
Theoretical analysis of resonant tunneling through finite superlattices
Authors: Kato Fumio 
Published: July 2007

AbstractA theoretical study has been carried out with a view to understanding the resonant tunneling phenomena in superlattice structures. For a general potential distribution, the resonance condition is derived and the relationship is found between the resonance levels and the subbands in an infinite superlattice. Especially, the relationship is studied between the resonance characteristics of a unit superlattice section with an arbitrary potential distribution and those of an n‐period superlattice made of n stages of unit superlattices. It is found that the discriminating function of the n‐period superlattice is given by a Chebyshev polynomial of that of the unit section. Hence, if any potential distribution (including an asymmetric one) is repeated at least twice, a resonance level can always be generated in each subband (with a zero bias voltage). A method based on this fact is presented for generating a resonance at an arbitrary energy level in an n‐period superlattice. Further, by way of these discussions, it is pointed out that there exist higher‐order resonances. An example for this phenomenon is presented.
Polymer thin film waveguide polarizer with a‐Si: H clad
Authors: Kato Isamu , Sugiyama Yasuyuki , Sugita Kotaro 
Published: July 2007

AbstractA device has been fabricated by loading an a‐Si:H film on a polymer thin‐film optical waveguide via a low index buffer layer. As an application to an optical functional device, this structure has been investigated as to its characteristics as a TE‐TM mode waveguide polarizer. In the present waveguide polarizer, the transmission mode can be selected by varying the thickness of the a‐Si:H film. In addition to the TE mode pass polarizer, a TM mode pass polarizer has been fabricated and studied which is not easily realized with a metal loaded structure. Both a slab waveguide and a practically important three‐dimensional waveguide (width 100 μm, 50 μm, 10 μm and 5 μm) have been used. In the case of a slab waveguide, both the TE mode and TM mode pass polarizers have exhibited an extinction ratio of 30 dB. In the case of a three‐dimensional waveguide, the extinction ratio is somewhat lower because the electric field distribution of the guided mode is a hybrid of the TE and TM modes. Nevertheless, the polarizer has a good extinction ratio.
An analysis of semiconductor waveguides with strip‐shaped plasma and their applications
Authors: Shimasaki Hitoshi , Tsutsumi Makoto , Kumagai Nobuaki 
Published: July 2007

AbstractWhen a high‐resistivity semiconductor is used as a waveguide medium which is illuminated optically so that the electron‐hole plasma is excited, its permittivity changes and the control of the propagation characteristics of the millimeter‐wave becomes possible. This paper studies the effect of the plasma layer width on the propagation characteristics in a waveguide with plasma induced on the grounded semiconductor slab. The hybrid guided mode was analyzed by means of the mode matching method. It is found that the attenuation of the wave increases as the plasma layer width is decreased if the plasma density per unit area is more than 1017.5 m−2. Further, the obtained results were extended and the characteristics of an optically controlled coupler made of dielectric waveguides were analyzed.
Analysis of high‐power short millimeter wave generation by reflection at the front of a relativistic electron beam
Authors: Ishido Yoshinari , Shiozawa Toshiyuki 
Published: July 2007

AbstractThe mechanism of generating high‐power short millimeter waves by means of reflection from the front of a relativistic electron beam is clarified quantitatively by using a two‐dimensional model made of two parallel conducting plates and a relativistic electron beam with arbitrary thickness sandwiched between them. First, in the laboratory frame, an incident wave of the lowest‐order odd symmetric TE mode is assumed. By way of the Lorentz transformation, the incident wave is transformed to the beam frame. Next, in the beam frame, higher‐order modes are considered for both the reflected and transmitted waves. By applying the mode matching method to the boundary conditions at the beam front, the electromagnetic field components of the reflected modes are derived. Then, when the Lorentz transformation is applied to these reflected waves, the electromagnetic field components of the reflected wave in the laboratory frame are obtained. Finally, the reflection characteristics are investigated numerically. It is found that the reflection coefficient becomes large in the total reflection region of the second‐order mode as well as in the total reflection region of the dominant mode and that the former has a broader bandwidth with more uniform characteristics than the latter. Also, there exists an optimum value of the beam thickness for which the power reflection coefficient is maximum.
Compression of picosecond optical pulses from a strongly RF modulated InGaAsP DBR diode laser using a gires‐tournois interferometer
Authors: Zhang Nai , Terukina Asao , Ito Hiromasa , Inaba Humio 
Published: July 2007

AbstractIn ultrashort optical pulse generation by gain switching of semiconductor lasers, the chirping phenomenon that is the shift in the oscillation wavelength based on refractive‐index changes due to carrier fluctuations, is well known. Using this chirping phenomenon, it is possible to have direct pulse compression in conjunction with a dispersive device. However, since the output power of semiconductor lasers is usually smaller than that of other types of lasers, efficient optical compression systems are indispensable. In this paper, use of the dispersion of Gires‐Tournois (GT) interferometer is proposed and its dispersion characteristics are investigated. Then, using the GT interferometer, 6.5 ps optical pulses are obtained by the compression of the chirped 30 ps optical pulsed from a distributed Bragg reflector (DBR) InGaAsP laser at 1.3 μm band by application of a strong RF modulation. The corresponding compression ratio is 4.6 with the peak power of 200 mW. Therefore, the usefulness of GT interferometer as the compressing device is confirmed.
Equivalent circuit model for positive/negative reflection—type SAW reflectors
Authors: Mitobe Seiichi , Koshiba Masanori 
Published: July 2007

AbstractAn analysis method is proposed herein which uses an equivalent circuit model as a means to evaluate positive/negative reflection‐type (PNR) SAW reflectors. The PNR reflector consists of reflecting elements which have 180° phase difference (positive and negative reflection coefficients). Each element is spaced with a period of one‐quarter wavelength. Compared with the conventional reflectors, these new reflectors have larger reflection‐efficiencies. In this paper, an equivalent circuit model for the PNR reflectors is presented. Circuit parameters can be determined theoretically by applying the finite‐element method to an infinite array. Examples are computed for two kinds of PNR reflectors on 128° Y‐X LiNbO3 or ST‐X quartz substrate. For each of them, we determined the circuit parameters and analyzed the reflection characteristics. We obtained good agreement between theoretical and experimental results.
A programmable optical demultiplexer using a 32–element photodiode array
Authors: Kinoshita Takeshi , Sano Ko‐Ichi 
Published: July 2007

AbstractThis paper describes the design and performance of a programmable optical demultiplexer which can compensate the influence of: (1) scattering in the wavelength of an optical source; and (2) wavelength fluctuation of the optical source caused by temperature change, by controlling the branching characteristics in accordance with the wavelength of the optical source. In this multiplexer, a 32‐element Si photodiode array was used to carry out programmable control of the branching characteristics. This optical demultiplexer has the following merits: (1) a wide channel passband is not needed; and (2) since the passband‐center wavelength of this multiplexer is adjusted to the wavelength of the optical sources, fine tuning of the branching characteristic in fabrication is not needed. The fabricated programmable optical demultiplexer has a channel wavelength spacing of 4.0 nm, an insertion loss of 8.0 dB which includes a loss of 3.9 dB due to the detection loss caused by the gap between two photodiodes composing the PD array, and a passband width of 2.8 nm. It was confirmed also by a digital transmission experiment (32 mB/s, RZ signal) that this demultiplexer can maintain its optimum branching characteristics for any wavelength deviation in the optical sources.
High speed, zero—bias modulation of low threshold MQW laser diodes
Authors: Nakamura Masaru , Furuyama Hideto , Kurobe Atsushi 
Published: July 2007

AbstractIn realizing high‐speed and very dense opto‐electronic integrated circuits with optical connecting inside and between the LSI chips, investigations are made on how to avoid the need for output power stabilizing and biasing circuitry of present semiconductor lasers. If it becomes possible to reduce sufficiently the threshold current of semiconductor lasers, in comparison to the driving current, its output stability against temperature variations improves and the delay time to switch it on can be reduced even at zero bias pulse driving. Using a GaAs/GaAlAs multiquantum well laser with threshold current of 4 mA, high—speed, zero‐bias and output control—free modulation experiments were performed. The requirement in optical communication systems for the output power variations to be less than ±0.5 dB was satisfied because for the temperature range of 0 – 50°C and at 20 mA driving current, the variations were limited to +0.45 –0.45 dB. At zero biasing the switch on delay of 150 ps was realized at pulse current of 34 mA with sufficiently good response to a 1 Gbps NRZ signal. The spectrum showed stable longitudinal multimode oscillation, and from its poor coherency, it was expected that stability against the returning light would be good. It is believed that obstacles in development of opto‐electronic circuits can be removed using semiconductor lasers with threshold current of a few milliamps.
Selective embedding epitaxial technique of highly resistive InP for OEIC's device isolation
Authors: Sugou Shigeo , Kasahara Kenichi , Murata Shigeru , Koizumi Yoshihiro , Kuroda Naotaka , Yanase Tomoo , Kato Yoshitake 
Published: July 2007

AbstractA device isolation layer for an opto‐electronics integrated circuit (OEIC) is desired to have not only an electrically isolating function but also an optical confinement function and low‐defect interface formation function. This paper describes a selective embedding epitaxial technique of highly resistive Fe‐doped InP by grown halide vapor phase epitaxy (VPE) for device isolation layer which has these functions. First, growth technique and growth conditions are examined for highly resistive Fe‐doped InP by grown hydride VPE, and it is shown that electrical characteristics sufficient for device isolation can be obtained. Also, characteristics of selective embedding growth are examined, and it is shown that a planar selective embedding growth is possible over a wide range of growth conditions. Furthermore, good results are obtained by applying this highly resistive layer to semiconductor lasers and OEIC devices.
Efficient finite—element formulation for analyzing the propagation characteristics of waveguides
Authors: Hano Mitsuo 
Published: July 2007

AbstractThis paper considers the finite‐element vector analysis of the dielectric waveguide, and derives a new finite‐element representation through a modification of the finite‐element representation by three components of electric on magnetic field. In the traditional finite‐element representation of this kind, the wavenumber k02 in free space is obtained as an eigenvalue for given propagation constant β. Consequently, a large amount of computation is required to determine the cutoff frequency of the waveguide or to analyze the waveguide with a medium with frequency dispersion. In this paper, a finite‐element representation for k0 is derived with β/k0 as the parameter, as well as the representation for β with k0 as the parameter. In those finite‐element representations, the matrix size is twice that of the traditional representation, but the approach is useful in terms of the computation time compared with the iterative method, since the solutions are obtained by one step. The finite‐element representation has essentially a feature that the physical and the spurious solutions can easily be discriminated by imposing the condition that the eigenvalue of the physical solution is real. Thus it is indicated that the finite‐element analysis based on the variational expression for the three components of electric or magnetic field is very versatile, where the solutions can be obtained for various parameters as required.
Coupling characteristics of crossover arranged rectangular dielectric waveguides
Authors: Matsumura Kazuhito , Tomabechi Yoshiro , Tsuchiya Noriaki 
Published: July 2007

AbstractThe coupling characteristics of two rectangular crossed‐over dielectric waveguides located on different parallel layers which presented a constant angle of intersection on a projection plane are analyzed. When two open waveguides were situated in proximity, each waveguide is mutually affected by the presence of other waveguide. Distributions of propagating modes in each waveguide were perturbed. This paper considers such perturbations using the authors' analysis method for a coupled system in a parallel arrangement. The coupled part is approximated by a step‐like approximation, and the dependence of the coupled electric power along each waveguide on the angle of intersection and the separation distance between upper and lower guides were clarified. Good agreement was obtained between calculated values and experimental measurements, in particular, the case of a tight coupling for a small separation distance between upper and lower waveguides and for the case of a large separation distance with a small angle of intersection with a long coupling part along the axial direction of the waveguides. This paper has improved greatly the authors' previous calculation results in which variational calculus was used on the assumption of a weak coupling. These results are considered to contribute to designing coupled circuits between upper and lower layers of integrated circuits for optical integrated circuits.
Preparation of superconducting thin films of a new oxide system by rf magnetron sputtering
Authors: Setsune Kentaro , Kamada Takeshi , Hirochi Kumiko , Adachi Hideaki , Wasa Kiyotaka 
Published: July 2007

AbstractLa‐Sr‐Cu‐O, Y‐Ba‐Cu‐O, and Er‐Ba‐Cu‐O ceramic thin films are formed by rf magnetron sputtering and subsequent annealing. The sputtering condition, the crystallinity of the films and the superconductive characteristics of the films were evaluated. The composition of the films depended strongly on the partial pressure of oxygen in the sputtering gas, and the resistivity of the films depended on the total sputtering gas pressure. The crystallinity of the films depends on the substrate temperature during deposition and is not affected by post‐annealing. The preferential growth of films occurred on sapphire substrates heated up to the temperature of higher than 650°C in a [001] direction which is normal to the substrate. Even when Er is substituted for the Y element in the Y‐Ba‐Cu‐O system, the film can be prepared under conditions similar to that of depositing a Y‐Ba‐Cu‐O film.
Equivalent circuit analysis of performance of acousto—optic deflector using liquid—loaded interdigital transducer
Authors: Toda Kohji , Urabe Heijiro 
Published: July 2007

AbstractAn acoustic wave can be generated in a liquid by operating an interdigital transducer (IDT) at a solid‐liquid interface. This paper describes the operation characteristics of an optical deflector in which the acoustic wave thus generated is used as a grating. By representing the admittance characteristics of the IDT as a function of the relative acoustic impedance of the liquid used as a load, the evaluation of the electroacoustic conversion efficiency and the characteristics as an AO device is simplified. By means of a broadband IDT with chirped electrodes, an acoustic diffraction grating is formed in water. Investigations of the characteristics as an acousto‐optic deflector reveal excellent results in diffraction efficiency, deflection bandwidth and resolution number.
Fiber‐optic gyroscope by interference fringes of bifocal lens optical system
Authors: Okada Sadayuki , Sonobe Hisao , Miyazaki Rokuroo 
Published: July 2007

AbstractThe interference‐type fiber‐optic gyroscope detects rotating angular velocity by means of interference between two optical signals traversing a fiber‐optic loop in opposite directions. In one method, the optical paths of two signals are completely equalized. In another method, the interference fringes obtained by adjustment of the lens location are used. This paper describes the second method. By means of a microoptic system using a bifocal lens, linear interference fringes are formed. After these fringes are read by a line scanner, the waveform is Fourier transformed so that the rotating angular velocity is derived from the obtained phase‐shift quantity. The results of the experiment indicate that the relationship between the input angular velocity and the output is linear over a broad range. A rotation of 0.02 to 182 deg/s was detected and the minimum output ripple at the time of detection was ±0.015 deg/s. The drift of temperature change was 0.03 deg/s per 0.01°C, and hence this method is sensitive to temperature variation.
Pulse operation of GaAs/ALGaAs surface‐emitting laser‐type optical threshold device
Authors: Nitta Jun , Koyama Fumio , Iga Kenichi 
Published: July 2007

AbstractThis paper describes the fabrication and basic properties and optical property of a GaAs/AlGaAs surface‐emitting laser‐type optical threshold device. Initially, a GaAs/AlGa‐As surface‐emitting optical threshold device with a mesa cap ring electrode structure (active layer of 3 μm and absorption layer of 0.5 μm) was fabricated and it was found that the device had a threshold current of 430 mA under room temperature pulse operation. To confirm whether the absorption layer was effective, the slow pulse response was calculated theoretically. Then, it was confirmed that an asymmetrical optical pulse can be obtained experimentally. Then a nonlinear optical input‐output was obtained at the input optical density of about 100 W/cm2.
Matrix solver with three‐dimensional VLSI technology
Authors: Kurokawa Takakazu , Ajioka Yoshiaki , Aiso Hideo 
Published: July 2007

AbstractA “Matrix Solver” is proposed for solving any type of linear equation over GF(2), with applications in cryptography and Error Correcting Codes.A design of the Matrix Solver is discussed as one of the appropriate applications of 3‐D VLSI systems. First, an algorithm based on the Cramer method combined with the Chio method is constructed following six new criteria for 3‐D VLSI algorithms. Second, a 3‐D layout and an implementation of a 3‐D structured breadboard model of the Matrix Solver are discussed.
Alpha‐particle induced source‐drain penetration (Alpen) effects
Authors: Hisamoto Digh , Toyabe Tohru , Takeda Eiji 
Published: July 2007

AbstractThe source‐drain penetration (ALPEN) effect, which is a new α‐particle induced soft error mechanism, was found and investigated by using a 3‐dimensional simulation. When an α‐particle penetrates the source‐drain region of a short channel MOSFET, the funneling field extends from both electrodes and the channel potential becomes distorted, thereby causing a funneling current. Since this current causes a charge leakage, it causes “0” → “1” reverse mode soft error in the DRAM in addition to the conventional α‐particle soft error. This error mechanism was also confirmed experimentally. The influence of this effect on future devices is predicted, and it has been shown that a device with a channel length shorter than 0.5 μm is influenced strongly by this effect. Therefore, it was concluded that this effect is an important factor in the scaling limit of a device.
Influence of the Ta migration on dielectric properties of anodized Al‐Ta(N)‐Al trilayered oxide films
Authors: Dobashi Tsuyoshi , Umezawa Toshiji , Sasaki Katsutaka , Noya Atsushi 
Published: July 2007

AbstractA trilayered dielectric thin‐film capacitor with an A1‐A12O3‐Ta2O5 (N)‐A12O3‐A1 structure was formed by anodizing a trilayered thin‐film, A1‐Ta(N)‐A1, deposited by RF diode sputtering. During the anodization procedure, Ta migrates into the aluminum oxide layer. The effect of Ta migration on the stoichiometry of the aluminum oxide was investigated by AES/XPS analysis before and after heat treatment. The results of the analysis showed that the migrated Ta's were in metallic and oxide states. However, the majority of the migrated Ta was in the metallic state, while the majority of A1 was in an oxide state. When the sample was heat treated in air at 300°C, oxidization of A1 progressed, but Ta tended to be reduced. Therefore, when a capacitor with a thick Ta film is heat treated, tanδ increases. If the thickness of the Ta layer is chosen properly, the stoichiometry of the A1‐oxide improves, resulting in a low tanδ (tanδ = 0.0018).