bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and characteristics of an optical wave meter
Authors: Okada Kenji 
Published: July 2007

AbstractA new optical wavemeter using a quartz azimuth rotator for direct reading of wavelength is described. When linearly polarized light having a certain wavelength enters the quartz rotator the plane of polarization rotates, the angle of rotation depending on the thickness of the quartz and the wavelength. Since the thickness of the quartz in the wavemeter is kept constant, the wavelength can be read from the angle of rotation of the polarized input light. This angle is obtained from the ratio of two polarized light beams which are divided from the input light by using an optical analyzer. The quartz thickness at which the error in measurement of wavelength is minimum is found. The relationship between the dividing ratio of the beams and the wavelength is also found. An azimuth quartz rotator with optimum thickness is fabricated. It is confirmed that the calculated and measured characteristics of the dividing ratio versus wavelength are in good agreement. The wavemeter has a wavelength range of 0.6‐1.6 μm and measurement accuracy better than 1 nm at input power of ‐35 dBm. To increase the utility of the wavemeter, a device to measure its input power with high sensitivity is added to the apparatus, the resulting accuracy being better than 0.1 dB at an input level of ‐35 dBm.
1.5 μm ingaasp fabry‐perot cavity‐type laser amplifiers
Authors: Mukai Takaaki , Saitoh Tadashi , Mikami Osantu 
Published: July 2007

AbstractTo understand the small‐signal gain, signal‐gain saturation and noise characteristics of 1.5 μm InGaAsP Fabry‐Perot cavity‐type laser amplifiers, two types of laser amplifiers having different thickness of the active layers were tested. It was found that the larger the gain coefficient (i.e., the larger the injected carrier density), the higher the gain and saturation output of the amplifiers, and the lower the noise level. Stern's gain calculation method was applied to materials for the 1.5‐μm region. It was found theoretically that these characteristics are due to the dependence of the carrier lifetime on the injected carrier density and the dependence of the saturation intensity and the population inversion parameter of the gain coefficient, by using the material parameters taking account of the Auger effect and the structure parameters of the device. The feature of the 1.5‐μm amplifiers is that the reduction of the carrier lifetime with the increase of the carrier density becomes more significant due to the Auger recombination process. It is important for improving the saturation output by positively utilizing this phenomenon to design the amplifier structure so that the amplifiers can be operated in a high‐gain region.
High‐linearity and high‐speed CMOS 1‐chip A/D, D/A converters. all‐digital linearity error correction (LECS)
Authors: Matsuya Yasuyuki , Akazawa Yukio , Iwata Atsushi 
Published: July 2007

AbstractThis paper describes an all‐digital linearity error correction (LECS) method for A/D and D/A converters, and presents the design and performance of single‐chip CMOS LSI converters utilizing this new technique.In general, the deterioration of converter accuracy is caused by discontinuity changes (jumps) of the converter characteristics due to component tolerances in the weighting network. The proposed correction method is based on a design ensuring that only negative jumps occur which are then eliminated digitally by a shifting of digital output (input) codes. Since this method does not require analog circuits, the number of noise sources is minimum and high reliability is achieved by eliminating physical trimming.Experimental CMOS converters have been realized utilizing the proposed method; the D/A converter provides an S/N of 92 dB at 150 ksps, and 87 dB is achieved by the A/D at 78 ksps. Thus, the possibility of realizing high‐quality audio converters by MOS process technology has been demonstrated.
Finite element analysis of the waveguide eigenmodes‐a novel method of employing transverse electromagnetic fields
Authors: Matsuhara Masanori , Angkaew Tuptim , Kumagai Nobuaki 
Published: July 2007

AbstractThere are numerous reports on the numerical analysis of variational expressions for a waveguide with an arbitrary cross section and structure by means of a finite element method. In conventional methods, cumbersome procedures or special programming techniques are required to discriminate the true solution of the guided mode from the spurious solutions. In this paper, a new variational expression for the β propagation constant is derived in which the transverse electromagnetic field components e.t and ht are used as the testing functions. A method is presented for numerical analysis of this new variational expression by means of the finite element method. It is pointed out that the guided mode and the spurious mode can easily and completely be discriminated by only the realistic condition that the propagation constant of the guided mode is real, without resorting to cumbersome procedures or special programming techniques. The new variational expression is well suited for a finite element analysis and resolves difficulties and ambiguities associated with the finite element methods based on the conventional variational expressions.
Studies of fabrication process for logic gate array using Pb‐alloy josephson junction
Authors: Hirano Mikio , Yano Shinichiro , Yamada Hiroji , Kawabe Ushio 
Published: July 2007

AbstractUsing a Pb‐alloy Josephson integration process with basic rules of junction dimension 3.5 μmϕ, minimum line width 2.5 μm, and junction current density Jc = 500 A/cm2, a Josephson logic gate array with integration of 576 gates/chip has been fabricated. For the device fabricated in the Pb‐In‐Au/oxide/Pb‐Bi system, hillocks have been observed in the base electrode film, and voids frequently occur in the counter‐electrode film, with the junction being short. This failure has been attributed to the electromigration of Bi in the counter electrode into the base electrode, thereby breaking the junction. Using a Pb‐In‐Au film formed at low temperature (∼0°C) for a base electrode and a Pb‐Au film for a counter electrode, junction shorts have been eliminated completely. A junction current variation of ±10% has been obtained which is one‐half that for conventional junctions. The yield for good chips by visual inspection is 10 30 percent. The delay time of signal propagation has been measured by the operation of various gate chain circuits using fabricated logic array chips. The gate delay time of 33 ps for the 2‐input OR gate and 54 ps for the 2‐input AND gate has been obtained.
A pulse‐driven PNPN switch circuit
Authors: Inabe Yasunobu , Hayashi Toshio , Kimura Tadakatsu , Tanabe Masaaki 
Published: July 2007

AbstractThis paper describes the design method of a pulse‐driven PNPN switch circuit which utilizes the N‐region carrier storage. Features of the circuit are: (1) there are no dc‐gate leakage current to the main current circuit, (2) the leakage of the pulse gate current to the main current circuit can be prevented by applying pulses to the P‐gate and the cathode (in a reverse phase), (3) both the driving circuit and the PNPN switch can easily be mounted on the same chip, (4) the P‐gate cathode stabilizing resistance and the dv/dt protection circuit can be applied as a conventional PNPN switch, and (5) the on‐state of the switch can be held even in a region where the anode current is smaller than the holding current by applying the gate pulse repeatedly. The relationship between the turn‐on characteristic of the fundamental PNPN switch and the circuit parameters were made clear by comparing the circuit equations with the experimental results. Based on these comparisons, the pulse‐driven PNPN switch was designed, and a good agreement between the design formulae and experimental results was confirmed. The condition which can avoid the false ignition of other PNPN switches on the same chip was analyzed. Consequently, the integration of multiple switches on a single chip became possible.
Room temperature pulse operation of GaAs surface‐emitting laser by using TiO2/SiO2 dielectric multilayer reflector
Authors: Kinoshita Susumu , Kobayashi Takahiro , Sakaguchi Takahiro , Odagawa Tetsufumi , Iga Kenichi 
Published: July 2007

AbstractAn Au‐evaporated film has conventionally been used as a reflecting mirror on the front side of GaAs surface emitting lasers to realize high reflectivity of the cavity ends. However, since Au‐evaporated films absorb light, the maximum reflectivity possible without drastically reducing the output efficiency has been around 85%. Therefore, in this work, a TiO2/SiO2 dielectric multilayer reflector has been used as a reflecting mirror on the front side. After the evaporation equipment is designed and fabricated, five pairs of TiO2/SiO2 dielectric films are formed on a GaAs substrate and its reflectivity characteristics evaluated. A peak reflectivity of 90% has been realized at 0.88 μm which is the resonant wave length of GaAs lasers. Next, five pairs of TiO2/ SiO2 dielectric multilayers are formed on an actual surface‐emitting laser and its laser characteristics are measured, with a resulting threshold current of 400 mA under a pulsed operation at room temperature.
Numerical analysis of radiation effects in MOS capacitors
Authors: Sano Eiichi , Kimura Tadakatsu 
Published: July 2007

AbstractThe Poisson equation, current‐continuity equations and rate equations for charged traps were solved numerically to analyze the flat‐band voltage shift due to irradiation for MOS capacitors. Good agreement was obtained between computed and previously reported flat‐band voltage shift dependence on gate voltage during irradiation, accumulated dose and oxide thickness. The physical meaning of the flat‐band voltage shift was clarified for the distributions of calculated charged traps and electrostatic potential. Moreover, the influence of electron hole mobilities, and trap density on the flat‐band voltage shift is discussed.
Design for SMF optical focusing‐beam system using GRIN rod lens
Authors: Kishimoto Ryozo 
Published: July 2007

AbstractOptical communication systems using single mode fiber (SMF) with a low loss and a broad band are promising for a long distance large capacity transmission. In this paper, we found a design guideline for the actual accuracy required in the fabrication and for realizing a low insertion loss LD module essential for the system realization. A modal expansion method has been used for analysis of the coupling system with a GRIN rod lens created on one end of the fiber for an efficient coupling. Next, coupling experiments have been carried out to confirm the validity of the theoretical analysis. In addition, a low loss coupling system with a coupling loss of about 2.8 dB has been realized. Allowable displacements have been studied which determine the practical accuracy in the fabrication of the LD module. It is found that a coupling system with a large tolerance in displacement allowance can be realized with a focusing rod lens.
Characteristics of DC–to–DC converters operating in current programmed mode
Authors: Harada Koosuke , Sato Terukazu , Miyazaki Izumo 
Published: July 2007

AbstractThe switching regulator is a device which controls the output voltage by on‐off (duty‐) ratio of the switching. One of the methods to control the duty‐ratio is the current programmed control, where the switch is turned on by the clock of the specified frequency and off when the switching current or the reactor current reaches the specified value. This paper considers the step‐up (buck‐boost) circuit as an example of the current programmed dc‐to‐dc converter. Analyses are made for the steady‐state characteristics, dynamic characteristics and the stability, using the state‐space averaging. The result is compared with that of experiment. It is shown that the peak current control circuit is essentially of constant‐current characteristics and can easily be protected against overcurrent. It is also seen that not only can the capacity of the circuit be expanded easily by parallel connection, but also the circuit has better characteristics against input variation than the earlier power supplies employing the duty‐ratio control.
Stability of magnetic and magneto–optical properties of tbco sputtered films
Authors: Tokunaga Takashi , Haradas Mitsuaki , Honda Shigeo , Ohkoshi Masatoshi , Kusuda Tetsuzo 
Published: July 2007

AbstractNoncrystalline TbCo films were formed by sputtering. Single‐layered films, 1000 Å in thickness without protective layer, were deposited, with the substrate biasing potential VB varied from 0 to −200 V. The room temperature stability of the magnetic and magneto‐optical properties of the films in atmosphere were investigated. The dependence of the magnetic property on the deposition conditions (VB and Ar pressure) was also investigated and it was found that the TbCo film became a film magnetized in a normal direction (normally magnetized film) under a certain condition. The saturated magnetization Ms changed to the Co‐rich side with time because of the selected oxidization of Tb atoms. The change of Ms was dependent on VB and became more rapid as the bias voltage increased. This was related to the film structure, and was considered to be due to the fact that the film became porous when the bias voltage was between −150 and −200 V and the oxygen diffusion to the film became easier. The reaction during this process is diffusion‐dominant. There was no time‐dependence in the Faraday rotational angle θf at the saturated magnetization but the Kerr rotational angle increased as the oxidation progressed. The normally magnetized film was formed when VB × 0 and the Ar pressure was 10 mtorr or when VB was between −100 and −150 V.
A josephson timed regulator
Authors: Ohhata Masanobu 
Published: July 2007

AbstractA Josephson timed regulator has been designed and tested which supplies timed bias current to logic gates, such as EX‐OR and NOT gates. This regulator consists of four SQUIDs in series, where the output line is coupled twice to each SQUID. In addition, this output line functions as the SQUID control line. As a result, all SQUID junctions are able to simultaneously switch even if the junction critical current is scattered. This regulator is fabricated using Pb alloy technology, successfully tested, and then favorably compared with computer simulation results.
Forming process in Al‐Al2O3‐au sandwich structures
Authors: Hirano Mikio , Miyamoto Nobuo , Matsumoto Goro 
Published: July 2007

AbstractThis paper discusses the forming phenomena under a high‐electric field using an Al‐Al2O3‐Au sandwich structure with a 10 60 nm thick Al2O3 film. When an electric field of ∼106 V/cm is applied to the sandwich structure in a vacuum lower than 1 Pa, the transition of the high‐resistance state to the low‐resistance state, so‐called “forming,” is observed. During the forming process, the injection of Au to the Al2O3 film formed the electric leakage path and the local structural change in both the Al electrode (the negative electrode) and the Al2O3 film occurred. The appearance of the negative resistance seemed to be caused by the destruction and reconstruction of the electric path.The sandwich structure with an A12O3 film implanted with A1+, B+, O+, He+, N+ or Ar+ shows the pre‐forming phenomenon observed in a sample treated in a vacuum for the forming process. The negative resistance was observed at the beginning in this sample. The sample also shows negative resistance in air. The sandwich structure with Au*‐doped A12O3 shows both the pre‐forming phenomenon and the negative resistance in both vacuum and air.
Flux control characteristics of ferrite orthogonal core using magnetic fluid
Authors: Oka Hideo , Iwata Junzo 
Published: July 2007

AbstractBecause of its orthogonal flux control system, the ferrite orthogonal core holds promise as a vector sensor. The combination of such a core and a magnetic fluid is of interest for control of flux with a simple system.The results of experimental studies comparing vertical and tilted ferrite orthogonal cores in magnetic fluid indicate that the system can be used as a two‐dimensional inclinosensor.
Simultaneous stabilization of spectral linewidth and oscillation frequency of an external‐cavity laser diode by fiber‐optic ring‐resonators
Authors: Tai Shuichi , Kyuma Kazuo , Hamanaka Kohichi 
Published: July 2007

AbstractThe oscillation spectral linewidth and the oscillation frequency of a laser diode with an external cavity have been stabilized simultaneously with an optical fiber ring resonator used as a spectrum discriminator. Stabilization of the oscillation spectrum linewidth has been carried out with control of the phase of the fed‐back light and the oscillation frequency by control of the injected current. The oscillation spectral linewidth is 2 MHz and its fluctuation is less than 10 kHz p‐p and the equivalent oscillation frequency fluctuation is 2 MHz p‐p From these results, it is confirmed that an external cavity laser diode can be used as a light source of a ring resonator‐type fiber gyroscope.
Surface deformation of thin‐film magnetic disks and their stress analysis
Authors: Ohta Satoshi , Yoshimura Fumikazu , Terada Akira 
Published: July 2007

AbstractDeformation of a small area (≤ 40 μm) on a magnetic disk (anodized Al‐alloy substrate with γ Fe2O3. sputtered surface) due to an external force was investigated. The results are that: (1) the amount of deformation (elevation or depression) on the surface of the disk is proportional to the load applied in the test. The elevation ratio α (amount of elevation/amount of depression; about 1 for a noncompressive material) has a similar trend, although its increase rate depends on the thickness of the anodized layer δ; (2) in the range of experimental load (≤ 50 g), α is greater than 1 when 6 is small (< 10 μm), and α is smaller than 1 when δ is large. The former is caused by a plastic flow of the Al‐alloy onto the disk surface due to a crack on the anodized layer forming a porous scratch. In the latter, the anodized layer is hardly broken so that a plastic flow onto the disk surface is suppressed; and (3) the distribution of the stress in the substrate was analyzed by the finite‐element method. When δ is small (2 μm), the maximum tension‐stress and the maximum shear‐stress occur on the substrate surface; and when δ is large (11 μm), they occur near the boundary between the anodized layer and the Al‐alloy. These explain qualitatively the experimental results in (2).
Two‐dimensional analysis of thermal oxidation of silicon
Authors: Sakina Yasuharu , Ohno Tsuneo , Matsumoto Satoru 
Published: July 2007

AbstractThe dependence of the two‐dimensional oxidation of silicon on the temperature and the oxidation period was investigated. A (110) silicon wafer whose surface was step‐shaped by anisotropic etching was oxidized between 900 and 1150°C and the cross sections of the oxide layers at the upper and lower edges were observed by SEM. The numerical simulation of the oxide film growth was carried out by considering both the diffusion and the surface reaction at the Si/SiO2 interface of the oxidants. The result was compared with the experimental result, and no orientation dependence in the growth rate was observed at high oxidation temperature. However, at the lower temperature, the growth rate in the (110) surface was higher than that in the (100) surface. This is believed to be due to the fact that the thermal oxidation at high temperature is diffusion‐dominated, while at the lower temperature, it is dominated by the surface reaction. In the low‐temperature oxidation at the upper edge, there was considerable decrease in the growth rate at the corners and the shape of the film was deformed. However, no such observation was made in the high‐temperature oxidation. The reason for this is believed to be the stress caused by the low‐temperature oxidation and the stress relaxation during high‐temperature oxidation. On the other hand, regardless of the oxidation temperature, the oxide film was deformed at the corners of the lower edge. This is believed to be caused by the deficiency of the oxidant.
dv/dt drive circuit method for pnpn switch with dv/dt protection
Authors: Suzuki Masayoshi 
Published: July 2007

AbstractThis paper describes a dv/dt drive method in complex pnpn switch circuits with both large critical slew rate (200 V/0.2 μs) and high gate sensibility (0.1 mA). The circuit consists of a thyristor and the protective circuit composed of an npn transistor switch and a driver.However, a false dv/dt turn‐on phenomenon of the thyristor is found in this structure under the condition that the storage time of the transistor is shorter than the gate recovery time of the thyristor.To avoid this phenomenon, a new dv/dt drive method is proposed by using a pnp transistor instead of a diode in the protective circuit.
Dynamic characteristics of phase and series cascade voltage regulator and effects of ambient temperature
Authors: Matsuda Masanobu , Kanata Yakichi 
Published: July 2007

AbstractThe authors have developed a phase and series cascade voltage regulator which has comparable efficiency to a switching voltage regulator and a degree of ripple suppression and an accuracy as good as that of a series voltage regulator. In this device, the input voltage is adjusted by the thyristor phase control so that the collector‐to‐base voltage of the series control transistor is always zero. The static characteristics of the device have been reported. This paper presents the dynamic characteristics of the circuit and discusses the operating limit of the temperature characteristics. It is found that the frequency response is determined mainly by the operational amplifier and the series control transistor, and by the trigger period of the thyristor gate. The effect of the operational amplifier and the series control transistor in the series regulator is especially significant, but the phase control rectifier exerts less influence on the frequency characteristics. On the other hand, the operating limit of the temperature characteristics is determined by the minimum firing phase angle. Except for cases of circuits operated near the lower limit of the input‐output characteristics and near the full load current, the operating range is found to be extremely wide. A practical circuit is used for confirmation of the stability of the circuit and the frequency response for the fundamental characteristics. In addition, the operating limit of the temperature characteristics and the effect of the ambient temperature on the operating limits of the input‐output characteristics and the load characteristics are studied theoretically and experimentally.
Third‐order digital phase‐locked loop with improved stability
Authors: Yamasaki Shoichiro , Nakagawa Masao 
Published: July 2007

AbstractWhen a signal from a moving source is received by a phase‐locked loop (PLL), the input‐signal frequency of the PLL often changes in a ramp‐function state with a constant‐frequency offset. In such a case, a perfect third‐order PLL is needed to track the signal without steady‐state phase error. The conventional perfect‐integration third‐order PLL has a serious problem of being unstable for small‐amplitude inputs, and thus it cannot be used in practice in a low SNR environment.This paper proposes three types of stable perfect third‐order digital PLL's (M‐DPLL) which are independent of the input‐signal amplitude. This M‐DPLL realizes the perfect third‐order behavior by combining three first‐order DPLLs using a digital signal processing technique. The excellent characteristics of this M‐DPLL are confirmed by theoretical analysis and computer simulation.