bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and electrical properties of V3Si films formed by solid–phase–reaction
Authors: Sorimachi Yoshio , Matsumura Tamio , Yamashita Tsutomu , Tsubata Ichiro , Miyauchi Shinnosuke 
Published: July 2007

AbstractThis paper describes the structural and electrical properties of V3Si films formed by solid‐phase‐reaction for Josephson superconductive thin‐film devices. To evaluate the film structure, the high‐speed ion backscattering technique, X‐ray diffraction technique, and SEM technique were employed. The resistivity of the film was measured by the four‐terminal method at temperatures between 4.2 and 300°K. In addition, the sueprconductive transition temperature was obtained. From these results, the following observations were made: (1) the V3Si phase is formed by using a V film on a thermally oxidized Si substrate, but there is a minimum SiO2 thickness depending on the temperature for the thermal treatment; (2) a V3Si film can be formed on either amorphous silica glass or single‐crystalline quartz. However, when the V3Si film forms on the silica glass, it tends to crack and has a large ΔTc. When the film is formed on a single‐crystalline quartz, there is a strong growth preferentially, and ΔTc is smaller; (3) Tc is dependent on the thickness of the V film and the thickness of the V film should be more than 1500 Å to obtain Tc higher than 10 K.
Laser damage threshold of KDP single crystal at 1.053 μm
Authors: Shimomura Osamu , Yokotani Atsushi , Sasaki Takatomo , Yoshidas Kunio , Yamanaka Chiyoe 
Published: July 2007

AbstractLarge KDP crystals having a high damage threshold against laser light are required for harmonic generation of a 1.053 μm high‐power glass laser system for nuclear fusion experiment. We studied the internal damage threshold of KDP crystals at 1.053 μm, 1‐ns pulsewidth.For the crystals grown by the temperature falling method, the damage thresholds of 8.3, 7.3, 6.1, and 11.2 J/cm2 were obtained for the KDP samples having a laser irradiated surface cut perpedicular to the (010) direction ([010] sample), parallel to the (101) surface ((101) sample), type I cut (type I sample), and type II cut (type II sample) of phase matching angle. The sample cut from the prismatic sector showed an anomalously large value of threshold 34 J/cm2.For the crystals grown by the electro‐dialysis method, 3.3, 5.0, 5.9, and 6.9 J/cm2 were obtained for “[010],” “(101),” “type 1,” and “type II” samples, respectively.
Ar pressure dependence of saturation magnetization and film composition in TbCo and tbfe sputtered films
Authors: Ohbayashi Shigeki , Nawate Masahiko , Honda Shigeo , Kusuda Tetsuzo 
Published: July 2007

AbstractThe argon pressure dependence of saturation magnetization MS and film composition in TbCo and TbFe sputtered films under the substrate bias VB × 0 was investigated. It was found that the change in the shape of multitarget surfaces influences MS strongly. When the sputtering period was 60 min, the Ar pressure dependence of MS and the film composition were different in TbCo and TbFe films. This was found to be due to the existence of the composition gradient in the direction of the film thickness in the TbFe film deposited under high Ar pressure. As a result of investigating the multitarget surfaces, the Tb chip surface was found to be contaminated by TM atoms (Co, Fe) and the intermetallic compound was formed. On the other hand, the TM target surface was clean. The surface condition of the Tb chip was different in the Tb ‐ Co and Tb ‐ Fe multitargets. The Tb surface of the Tb ‐ Fe target was covered with cone‐shaped projections, causing the composition gradient in the film thickness direction when the Ar pressure was high. When the sputtering period was short (shorter than 12 min), the composition ratio against NTM/NTb) against MS and Tb decreases with the increase of Ar pressure in both depositions of TbCo and TbFe films.
Wide Frequency‐Modulation Operation of Semiconductor Lasers Using a Composite‐Optical Cavity
Authors: Nagata Masaya , Ohtaka Masato , Kobayashi Takao 
Published: July 2007

AbstractIn the optical heterodyne communication and measurement based on semiconductor lasers, selection of an arbitrary frequency within a broad gain spectral width and continuous and broadband FM operation are needed. This paper reports a theoretical study on a laser diode (LD) with a composite optical cavity using an external reflector. Using a GaAlAs LD with an adjacent plane or spherical mirror, a broadband tuning of oscillation frequency of about 8 THz (18 nm) becomes possible by variation of the external cavity length. Further, by modulation of the injection current, a continuous FM shift as large as 150 to 290 GHz is realizable which is three to five times the conventional value.
Study of GaAs FET process using focused ion beam lithography
Authors: Sasak Yoshinobu , Morimoto Hiroaki , Komaru Makio 
Published: July 2007

AbstractTo construct a highly efficient GaAs FET, it is effective to shorten the gate length. Focused ion beam lithography was utilized to form fine gates. For application of this technique to practical device fabrication, the exposure characteristics of PMMA and the damage to the substrate by the Si‐and Be‐focused ion beams have been investigated. A stable resist profile was obtained with a dose of 2 × 1013 ions/cm2. However, the exposure to the ion beams damaged the substrate. To eliminate this damage, a deep recessed structure was adopted and focused ion lithography was used for fabrication of an FET with low noise and medium output power. A gate length of 0.2 to 0.3 μm was realized and an improvement of the device characteristics was demonstrated. As the device structure becomes finer, the gate resistance increases. Therefore, a mushroom gate was formed to decrease the gate resistance. It was shown that focused ion beam lithography is an effective way to form an efficient GaAs FET.
Proposal of high speed bipolar‐CMOS merged VLSI technology and its future prospect
Authors: Watanabe Atsuo , Hiraisi Atsusi , Nagano Takahiro , Masuda Ikuro , Ikeda Takahide 
Published: July 2007

AbstractBiCMOS technologies are one of the promising candidates for the third generation LSI technology because it realizes high‐speed, high‐integration VLSIs utilizing the features of both the CMOS and bipolar devices. This paper discusses the device structure with respect to the speed‐up of BiCMOS basic circuits. First, the modeling of basic circuits and the numerical analysis of the bipolar operation indicate the importance of the vertical dimension of bipolar devices. Next, we have discussed a vertically miniaturized well structure without the degradation of the CMOS characteristics. A theoretical analysis clarified that the buried well structure with the combination of the shallow diffusion layer and the buried layer produces the minimum point of the impurity density and realizes both high‐speed bipolar device and fine‐pattern CMOS devices. On the basis of this, we have fabricated 1.2 μm gate CMOS devices and high‐speed bipolar devices with the break‐down voltage of 8 V and the maximum cut‐off frequency of 9 GHz on the same substrate and confirmed that the basic circuit constructed with these devices exhibits the delay time of 0.4 ns with the typical load capacitance and operating frequency. Furthermore, it is indicated that the performance of this basic circuit proceeds with the same ratio as that of CMOS circuits' devices based on the scaling law.
A 1‐GHz band low‐power dissipation GaAs prescaler IC
Authors: Maemura Kosei , Shimura Teruyuki 
Published: July 2007

AbstractIt is important that the power consumption by mobile communication equipment be reduced as much as possible from the viewpoint of miniaturization, weight reduction and battery operation. One approach to this problem has been the development of a dual modulus prescaler IC for 1/128 and 1/129 division in the 1‐GHz band with GaAs FET's capable of high‐speed operation and low power consumption. Since nonuniformity of device characteristics is still substantial in GaAs FET's, an optimization in the circuit design is needed whereby the characteristics of the FET are given sufficient consideration. In the design of the prescaler, the SCFL is used as a logic gate which has a broad tolerance in characteristic fluctuations of the FET. In addition to consideration of the operating margin and fan‐out characteristics, such design optimizations as the pattern orientation of the IC and the current distribution to each part have been carried out. With only one 5‐V power supply, the power supply current required has been less than 5 mA in the 1‐GHz band. This power consumption is less than half that used by the conventional SiECL IC. The design procedure and the results of the test fabrication are reported.
High–power HeCd+ white light laser
Authors: Fuke Akira , Masuda Katsuhiko , Tokita Yasuhiro 
Published: July 2007

AbstractThe hollow cathode HeCd+ laser includes twelve oscillation lines. The oscillation line of 441.6 nm (blue), 533.7 nm and 537.8 nm (green), and 635.5 nm and 636 nm (red) in the visible area can be oscillated concurrently by using wide‐band mirrors for a resonator to produce a white light laser. This laser is expected particularly in the image production industry because a single laser tube allows the three primary colors of light to be produced and the green wavelengths are optimum for green emulsion of photographic films. However, it has been difficult to produce the hollow cathode HeCd+ laser of continuous oscillation and high power. We have investigated the high power and output stability of the white light laser for practical purposes. As a result of examining the structure of the hollow cathode as a means for high‐power laser, we could realize a high‐power HeCd+ white light laser by using a new structure which was an improvement over the conventional flute type. This paper explains the structure of the hollow cathode and shows the dependencies of the output on the Cd vapor pressure, He pressure, input power for the cathode length of 61 or 43 cm, and the noise characteristics for the cathode length of 61 cm.
Single‐mode optical fibers with zero total dispersion at wavelength 1.3 and 1.55 μm. fiber with α‐power index core and triple clad
Authors: Nakazawa Kazushige , Hinata Takashi , Hosono Toshio , Furukawa Shinichi 
Published: July 2007

AbstractSingle‐mode optical fibers with an α‐power index core (α = 1, 2, 6, ∞) and a triple clad have been designed under the following two conditions: (I) the total dispersion at wavelengths of 1.3 and 1.55 μm is zero; and (II) the cut‐off wavelength λc for the second mode is less than 1.15 μm. In this paper, the sensitivity of the total dispersion, the equivalent bending radius (the radius at which the bending loss is 0.01 dB/km), and the splice loss of those fibers are discussed. The clad has an ideal triple layer structure (the relative index difference between the first and outer cladding is Δ2 and that between the second and outer cladding is Δ3). For a given value of α which determines the core refractive index profile, Δ1. (the relative index difference between the core and outer cladding), and a (core radius) can be chosen freely. In this paper, for a given α the fiber, satisfying conditions (I) and (II), was designed under the conditions that (1) Δ1 = const, and (2) \documentclass{article}\pagestyle{empty}\begin{document}$ A\mathop \Delta \limits_ = \int\limits_0^{a/w} {n(r/w,\;\lambda)dr\; = - const(w\mathop \Delta \limits_ = a + t_1 + t_2, t_m;} $\end{document} m‐th cladding layer width, m = 1, 2). Comparing the fiber with a core of α = 1, 2 and 6 (t2/t1 = 1.0, Δ2 < 0, Δ3 < 0), the step index core fiber (α = ∞). has the following characteristics whether the fiber is designed under condition (1) or (2): 1) a lower sensitivity for the core radius and wavelength; 2) a smaller equivalent bending radius; 3) a smaller splice loss in the case where d/a = const (d: axial displacement). For the case where α = ∞, the structure with Δ2 > 0 and Δ3 < 0 was investigated and compared with the structure with Δ2 < 0 and Δ3 > 0.
Millimeter wave dielectric waveguide isolator
Authors: Tanaka Katsuyuki , Tsutsumi Makoto , Kumagai Nobuaki 
Published: July 2007

AbstractA dielectric waveguide isolator with a new open structure is proposed which makes use of the magnetic loss of the ferrite. The analysis is not based on the conventional two‐dimensional approximation but is a rigorous three‐dimensional approach taking into account the waveguide width and is based on the mode matching method. From the numerical results, it is demonstrated that an isolator based on the TM excitation is possible which cannot be found by the two‐dimensional approach. Subsequently, the isolator is operated experimentally and the results are shown to agree well with the theoretical prediction. Further, as a method for development of the characteristics, the experimental results for the structure loaded with a lossy material are presented.
Guided modes of diffused slab waveguides
Authors: Yata Akira , Ikuno Hiroyoshi 
Published: July 2007

AbstractThe propagation constants and field distributions for the guided modes for diffused slab waveguides are evaluated by uniform asymptotic solutions. The effect of the upper layer of the substrate on the guided modes are obtained automatically by the use of parabolic cylinder functions of noninteger orders. Diffused waveguides which have complicated profiles of refractive index such as squared hyperbolic tangent and Gaussian profiles are considered. The accuracy of uniform asymptotic solutions is examined numerically. As a result, it was found that their solutions had a high accuracy and they clarified the behaviors of the fundamental mode in the frequency range for the single‐mode propagation. As analyses and design examples for a variety of waveguides, the relationship between the refractive index profile and the domain of the single mode propagation was examined. It was shown that the waveguides with Gaussian profile are superior to those with other types of profiles.
Fundamental study on a short distance measurement method by using a sinusoidal wave oscillator with light path as delay line
Authors: Sato Katsunori , Echigo Hiroshi , Takagi Tasuku 
Published: July 2007

AbstractConventional optical distance measurement systems are not convenient for short‐distance measurements. This paper proposes a system which can measure a short distance accurately and simply. This system is tested and investigated, and in this system, the optical path is contained in an oscillator. By changing the oscillation frequency by the optical path length, the distance is obtained from the frequency. From a portion of the experiment and a theoretical study, the possibility of a distance measurement system is investigated. The accuracy of the present system can be improved by raising the oscillation frequency. In the experiment, a 300‐m long optical fiber was measured within an error of 5.5 cm at the oscillation frequency of 1 MHz.
Analysis of groove guide for short‐millimeter waves
Authors: Tamura Hitoshi , Kurazono Sadao 
Published: July 2007

AbstractRequirements for waveguides of millimeter waves are demanding. Ongoing works have been conducted seeking waveguides with better characteristics. Many consider groove guides to be promising waveguides for short millimeter waves based on their easy manufacture and small influences due to bendings. However, earlier works on groove guides have focused on rectangular grooves. Their analyses were approximate and there were no rigorous analyses. This paper rigorously analyzed three types of groove guides via the method of boundary elements. We obtained the electromagnetic fields of the transmitted modes and various transmission properties such as cutoff frequencies, dispersion characteristics and attenuation characteristics. As a result, we clarified that groove waveguides had low losses and low dispersion. In practice, it may be possible to realize their uses for short millimeter waves.
A multiple‐ISFET integrated with CMOS interface circuits
Authors: Tsukada Keiji , Maruizumi Takuya , Miyagi Hiroyuki 
Published: July 2007

AbstractTo achieve the simultaneous measurements of ion concentrations with high accuracy using multiple ISFETs, the integration of multiple ISFETs with signal processing circuits has been attempted. To achieve process matching in the fabrication of the ISFETs and additional circuits, and to lower the power consumption, CMOS devices have been used for the signal circuits. The integrated circuits were composed of four ISFETs, a constant current source, a buffer amplifier, and a multiplexer. To measure ion concentration at high speed with a high degree of accuracy, each ISFET contained a source follower and a buffer amplifier to achieve an independent operation. Only the output signal was switched by a multiplexer. The average sensitivity of each ISFET was 54.4 mV/pH for the range of pH 1 to 10. The response time for an increase of the pH by 1 was about 1 s. The time needed to switch the output signal was 200 μs, which is three orders of magnitude faster than ion response speed. As a result, it was found that this integrated sensor structure was suitable for measuring the response of multiple ISFETs at high speed. This paper describes the sensor structure, the circuit design and its response characteristics.
Aberration of GRIN—rod lenses in single—mode optical fiber devices
Authors: Sumida Masatoyo , Takemoto Kenji 
Published: July 2007

AbstractGraded refractive index rod (GRIN‐rod) lenses are used widely in optical devices for optical fiber communication systems. Insertion loss is a major criterion for evaluating optical devices, especially those used in single‐mode fiber systems, and aberration is a dominant factor in insertion loss. Thus, aberration analysis is essential in designing high‐perfomance optical devices. This paper presents ray traces within the third‐order aberration when light propagates through GRIN‐rod lenses. Using the fact that the ray is the orthogonal trajectory of the wavefront, we derive a novel wave optical description of GRIN‐rod lenses to the degree of third‐order aberration. This paper shows the relatinship between coupling efficiency and lens parameters. The necessity of considering aberration effects in designing low insertion loss optical devices is shown. The experimental results are in very good agreement with the calculated values, and the validity of the present analysis is confirmed. This paper proves that GRIN‐rod lenses are superior to ball lenses in terms of aberration, and provide higher coupling efficiency.
Asymptotic approximation and experimental study of electromagnetic fields excited by an electric dipole located over a conducting concave spherical surface
Authors: Maeda Tadahiko , Sawaya Kunio , Adachi Saburo , Mushiake Yasuto 
Published: July 2007

AbstractThe dome antenna has been proposed for scanning an antenna beam at a high speed in a wide angular range. For the design of a dome antenna, an electromagnetic analysis in the concave side of the conducting sphere is required. In connection with this problem, the electromagnetic field by an electric dipole placed on the concave surface of an open conducting sphere has been reported and analyzed in terms of the sum of the whispering gallery (WG) modes, continuous spectrum and ν = 0 (ν: wavenumber in the θ direction) by the authors. However, it has been pointed out that this expression has a problem for an arbitrary ka, although it provides a valid result for ka = nπ/2 (k: wavenumber, a: sphere radius, n: integer). It is also unattractive numerically since Legendre functions must be calculated by numerical integration. In this paper, an engineering application is attempted by using a high‐frequency approximation. By means of the approximate asymptotic solution and the previous expression, actual numerical calculations have been carried out. By way of comparison with experimental results, the validity of each expression is confirmed and its range of applicability is studied.
Characteristics of MOS—FET PWM inverter with high carrier frequency
Authors: Nagao Michihiko , MacHitani Yooichi , Nakano Tadao 
Published: July 2007

AbstractSince a power MOS‐FET has a reverse diode located internally between the drain and source, when a PWM inverter is constructed with MOS‐FETs, a shunt phenomenon occurs between the upper and lower arms due to the recovery current of this internal diode. This phenomenon can effectively be prevented by limiting the current rise by an inductance. In this work, a PWM inverter with around 1 kW has been realized which operates with a high carrier frequency of about 100 kHz by using a close‐coupled inductor. Furthermore, as a design guideline for a PWM inverter, an analysis is made of the loss of each device and inverter efficiency and the experimental results are compared.
Miniaturized directional coupler—type optical switches
Authors: Minakata Makoto , Sakano Toshikazu , Kawakami Shojiro 
Published: July 2007

AbstractOptical switches not only find wide applications, but also are used in a matrix form. Hence, reduction of the single elements is important for improving the integration density and improving the characteristics of the bandwidth and insertion loss. In this paper, a fabrication guideline has been obtained for a miniaturized LiNbO3 directional coupler‐type optical switch. Next, based on the guideline, a device was fabricated, and the relationship of the waveguide spacing S to the coupling length L0 and the phase constant difference Δβ/C was measured by the monitor method using a metal loading. At the wavelength of λ = 1.15 μm, we obtained S = 1.7 μm, L0 = 1.6 mm (previously several millimeters) and Δβ/C = 0 as the minimum. Further, an optical switch with two divided electrodes was fabricated and the switch voltage of V0 = 12 V, extinction ratio of 9.8 dB, and optical insertion loss of 3.6 dB were obtained. Items to be investigated for further improvement are included.
Nonreciprocal phase characteristics of single—mode magneto—optic rib waveguides
Authors: Inuzuka Hirosei , Okamura Yasuyuki , Yamamoto Sadahiko 
Published: July 2007

AbstractThis paper describes the nonreciprocal phase characteristics of a magneto‐optic waveguide important for formation of nonreciprocal optical guided‐wave devices. Theoretical and experimental investigations are carried out for a single‐mode rib waveguide fabricated on an La‐ and Ga‐substituted YIG thin film. Usually, nonreciprocal phase characteristics are measured by means of the optical path length difference of a Mach‐Zehnder interferometer. In this paper, however, a simpler method is used in which a phase constant difference of two orthogonally polarized modes (the vertically polarized mode affected by an applied magnetic field and the horizontally polarized mode not affected by the applied magnetic field) in a straight waveguide is used. In confirmation of the nonreciprocity, the direction of the optical wave is reversed instead of the direction of the applied magnetic field. In the case of a conventional three‐layer structure (air/YIG/GGG substrate), the film thickness dependence of the nonreciprocity is measured. In addition to a rather good agreement with the theoretical value, existence of an optimum film thickness is confirmed. Further, an experiment is carried out for a four‐layer waveguide in which a high index layer (TiO2) is placed on YIG.As expected from the theory, it is confirmed that the nonreciprocity is increased to twice that of the unloaded structure. It is demonstrated that this configuration is effective for fabrication of a nonreciprocal phase shifter.