bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation characteristics of the magnetostatic surface wave in the composite structure of yttrium‐iron garnet film and YBCO
Authors: Fukusako Takeshi , Tsutsumi Makoto
Published: July 2007

The propagation characteristics of the magnetostatic surface wave in a composite waveguide with a YIG film and YBCO were investigated theoretically and experimentally.

First, using the equivalent complex permittivity of YBCO obtained by the two‐fluid model and the permeability tensor of a YIG film, the dispersion relationship of the waveguide was derived. It was proved theoretically that a strong nonreciprocity within the 2.4‐GHz bandwidth with low loss could be achieved by placing superconducting material in the waveguide. The influence of magnetic loss of YIG, ΔH, on the superconducting material also was discussed in detail and it was found that when ΔH exceeded 1 Oe, the effect on the loss reduction by YBCO disappeared.

The propagation characteristic of the magnetostatic surface wave in the waveguide with superconducting material was evaluated experimentally at liquid nitrogen temperature. Through a comparison of this result with that obtained in a waveguide with copper, nonreciprocity was discussed. In addition, the delay characteristic of the waveguide with a composite structure of YIG‐YBCO was demonstrated experimentally.
Transient scattering responses from a plane interface between dielectric half‐spaces
Authors: Shirai Hiroshi
Published: July 2007

The transient scattered electromagnetic field due to an impulsive line source placed near the boundary between two dielectric media is formulated by the Cagniard‐de Hoop method. The scattered field is divided into the direct wave and the reflected wave. Then the reflected wave is divided further into the conventional reflected wave, and the head wave contribution appearing in the total reflection region. The rigorous solutions for each contribution are obtained. The wavefront approximation that can be used immediately after the wave arrival also is derived. The relationship between the wavefront approximation and the high‐frequency asymptotic geometrical optics field derived in the frequency domain is discussed.
Location and profile of phase conjugate image with gaussian beam pumping
Authors: Okamoto Atsushi , Mishima Teruhito , Sato Kunihiro , Sakuraba Ichiro
Published: July 2007

When applying phase conjugate waves to various types of image processing, the characteristics of the wavefront, generated by the nonlinear optical medium, are an important research problem. The characteristics of a phase conjugate mirror with plane wave pumping have been investigated in previous research. To perform more realistic analysis, we derive equations describing the image location of the phase conjugate mirror with fundamental mode Gaussian beams as the pumping light and calculate the phase conjugate images numerically. The relationship between the probe light and the phase conjugate image using the Fresnel diffraction formula will be formulated first. Then the image location and the image magnification factor in consideration of the wave‐front curvature of the pump light is derived. Then the characteristics of the image location are analyzed considering the change of the curvature radius of the Gaussian beam in the thickness direction of the nonlinear optical medium. The image profile of the phase conjugate mirror is found by numerical calculation. The results show for the first time the effects of wavefront curvature of the pump light on the image reconstruction capability, which is an important characteristic of the phase conjugate mirror.
Nonradiative dielectric‐guide FM gunn oscillator at 60‐GHz band
Authors: Kuroki Futoshi , Baba Junnei , Furuya Hiroshi , Member Tsukasa Yoneyama
Published: July 2007

A nonradiative dielectric (NRD)‐guide FM Gunn oscillator with a built‐in circulator has been developed for the 60‐GHz frequency band, which has attracted considerable attention recently in Japan. In the fabrication of the 60‐GHz band NRD‐guide Gunn oscillator, a Gunn diode sealed in a specially fabricated compact package 1.2 mm in diameter has been used instead of the large‐diameter Gunn diode package commercially available. The oscillator has an output power above 130 mW, which is sufficient for practical applications.

An NRD‐guide circulator also is fabricated to protect the oscillator from reflected wave. Using NiZn ferrite material, much better performance is obtained compared to conventional microstripline circulators. A frequency modulator using a beam‐lead varactor diode has also been designed and fabricated. Emphasis has been placed on structural simplicity and modulation sensitivity. Based on all these, an FM Gunn oscillator is fabricated, and for a bias voltage of 15 V applied to the varactor diode, a frequency deviation of 260 MHz is obtained. This FM Gunn oscillator with built‐in circulator can be contained in a compact housing 3 cm × 3.5 cm.
Auger electron spectroscopy study of the solid‐phase reactions in Al3Zr/Zr/Si contact systems
Authors: Yanagisawa Hideto , Karasawa Hajime , Noya Atshshi , Sasaki Katsutaka
Published: July 2007

To obtain the fundamental understanding on the capability to apply the Zr film to Al metallization technology for Si‐LSI, interfacial solid‐phase reactions in Al/Zr/Si, Al‐Zr/Zr/Si, and Al3Zr/Zr/Si contact systems have been investigated by AES analysis. In the Al/Zr/Si system, Al and Zr layers reacted spontaneously and interdiffused each other even before the heat treatment. In the Al‐Zr/Zr/Si system, in which the Al overlayer was replaced with the Zr‐doped Al film, well‐separated interfaces of Al‐Zr/Zr and Zr/Si were observed before the heat treatment. But when heat treated at 400°C, Zr atoms in the Zr layer migrated into the Al‐Zr overlayer and the interposed Zr layer became too thin prior to the formation of the distinct Zr silicide layer. In the Al3Zr/Zr/Si system, the amorphous overlayer with the composition of Al3Zr recrystallized into a stable Al3Zr intermetallic compound during the heat treatment above 400°C. In this system, because the thermal equilibrium state is realized at the Al3Zr/Zr interface, a possible solid‐phase reaction is restricted only at the Zr/Si interface. Therefore, the system tolerates the temperatures up to 500°C and a stable Zr‐silicide layer can be formed at the Zr/Si interface.
Heat‐proof properties of Ta2N anodized thin‐film capacitors prepared at low anodization voltage
Authors: Sasaki Katsutaka , Yamane Misao , Abe Yoshio , Noya Atsushi
Published: July 2007

To clarify how the high heat‐proof properties of Ta2N anodized film capacitors are maintained when the film thickness is reduced, the effects of heat treatment temperature increase on dissipation factor (tan δ), temperature coefficient of capacitance and dc leakage current are studied for a capacitor formed by reducing the anodization voltage. The results will follow. Even for the anodized capacitor prepared at a reduced anodization voltage of 80 V, there is no thermal degradation in tan δ and temperature coefficient of capacitance for the heat treatment below 400°C. The leakage current also shows a qualitatively similar behavior for a reduced anodization voltage with no change in the electrical conduction mechanism, even when the anodization voltage is reduced. On the other hand, while the leakage current of this Ta2N anodized film formed at 80 V changes little up to a heat‐treatment temperature of 300°C, it increases rapidly at 350°C. However, compared to a Ta anodized film formed at 160 V anodization voltage with the same capacitance, this Ta2N anodized film formed at 80 V has a drastically improved heat resistance in terms of tan δ, temperature coefficient of capacitance and leakage current. From these results, it has been clarified that the use of Ta2N compound is an extremely effective way to maintain heat resistance while reducing the film thickness.
Novel two‐mode cutoff‐waveguide filters and their new design method
Authors: Iguchi Kazutaka , Tsuji Mikio , Members Hiroshi Shigesawa
Published: July 2007

This paper describes a new method of configuration of a cutoff waveguide filter with attenuation poles. When a filter with attenuation poles is constructed, often the degenerate mode is used or the filter configuration uses two paths. In this paper, a new configuration is presented in which the negative coupling between the TE101and TE201modes in a waveguide cavity is used. The test fabrication and experiment are carried out for both the cavity resonator loading and the dielectric resonator loading. The effectiveness of the present filter configuration and the design method is confirmed.
Optical design for large‐scale free‐space optical switching modules
Authors: Shirai Seiiti , Serikawa Tadashi
Published: July 2007

To achieve large‐scale and compact free‐space optical switching networks, highly efficient coupling between input and output fiber arrays and low‐loss beam propagation for a long‐span are required. In the cascaded optical beam‐shifter module using liquid‐crystal devices, beam expansion due to optical diffraction limits the scale of the switching network.

A microlens configuration consisting of collimating lenses and relay lenses with a long focal length is proposed for long‐span beam propagation. This lens configuration can reduce the limitation on the scale of switching network. It is shown that a large‐scale and compact optical switching network can be constructed. The relationship between the aperture size to determine the physical size of an optical switch and the focal lengths for the required lens system also are shown. A long focal‐length microlens fabricated using the sputter‐liftoff method was shown to be very useful for long‐span beam propagation.
A study on degradation of spatial resolution in frequency‐modulated continuous wave reflectometry due to nonlinear optical frequency sweep
Authors: Wang Lu‐Tang , Liyama Koichi , Hayashi Ken‐Ichi
Published: July 2007

The degradation of the spatial resolution in frequency‐modulated continuous wave (FMCW) reflec‐tometry due to the nonlinearity in the optical frequency sweep are discussed both experimentally and theoretically. The response lag in the optical frequency change of a laser diode behind the injection current change was experimentally measured, showing that there were several time constants in the optical frequency response. The interference signals in the FMCW reflectometry were theoretically calculated by taking account of the response lag. From these calculations, the beat frequency becomes low just after the turning point of the optical frequency sweep; this is due to the response lag in the optical frequency response. As a result, the spectrum of the interference signal is spread out toward the low frequency region and spatial resolution is degraded. Moreover, the spatial resolution is seriously degraded with increasing the diagnosing distance due to the nonlinearity in the optical frequency sweep. The calculated results agree well with the measured results.
Kinetic study of WSix‐CVD processes—a comparison of WF6/SiH4 and WF6/Si2H6 reaction systems
Authors: Saito Takeyasu , Shimogaki Yukihiro , Egashira Yasuyuki , Komiyama Hiroshi , Sugawara Katsuro , Takahiro Katsumi , Nagata Shinji , Yamaguchi Sadae
Published: July 2007

Kinetic study on chemical vapor deposition of tungsten silicide (CVD‐WSix) by the mixture of WF6/SiH4 or WF6/Si2H6 was made using an externally heated tubular reactor. By investigating the effect of the film precipitation area on the gas phase volume ratio (the S/V ratio) in film formation, it can be concluded that the initial step of film precipitation was dominated by radical chain reaction. In addition, a new process to form WSix using preliminary excitation of gas phase reaction at the inlet of the reactor was proposed. Using this process, film composition was controlled and the formation of WSi2.5 films with excellent step coverage was realized.
Copper self‐sputtering and filling of submicron holes
Authors: Asamaki Tatsuo , Miura Tsutomu
Published: July 2007

A new thin‐film technology using self‐sputtering, which sputters the target with its own ions only, not with inert gas ions, is investigated. In the present paper, the characteristics of self‐sputtering and filling of deep holes with metal are investigated. Self‐sputtering of copper is performed in a wide pressure range of 10−2 Pa to 10−4 Pa. A high target current of 7 A to 10 A for a 4‐inch planar magnetron target is essential for a self‐sputtering process that yields a very high deposition rate of about 4 μm/min at 60 mm from the target surface. Conditions for sustained self‐sputtering are determined.

Good bottom coverage of 100 percent is obtained in thinner film deposition (0.2 μm thick) and 50 percent coverage is obtained in thicker thin‐film deposition (1.2 μm thick); the submicron holes have a high aspect ratio of 2, an inlet diameter of 0.6 μm, and a depth of 1.2 μm. It is found that the bottom coverage β increases sharply when the ratio α = (distance between target and substrate)/(radius of erosion center ring) is larger than 2 and although at lower pressure the bottom coverage by self‐sputter deposition saturates at longer distances, the bottom coverage in conventional sputter deposition at 3 × 10−1 Pa decreases with distance after saturation. The bottom coverage β also decreases with increasing pressure, with the thickness of the deposited film and with the radial distance of the substrate position from the target center toward the erosion center.
Control of radical species in microwave plasma chemical vapor deposition
Authors: Kato Isamu , Yoneda Toshiyuki , Matsushita Toru , Yamashita Makoto
Published: July 2007

The spatial distributions of electron temperature and density in pure Ar plasma in a double‐tubed coaxial‐line type microwave plasma chemical vapor deposition (CVD) system were measured using the probe method. It was found that the electron temperature and electron density dropped sharply in an area 4 cm from the edge of the discharge tube and they decreased slowly in an area farther away from the forementioned area. SiH4 gas was dissociated in Ar plasma, and the electron temperature and density of the plasma were varied by changing the location of the SiH4 gas inlet. As a result, it was found that the fragmentation pattern of radical species could be varied by changing the location of the SiH4 gas inlet.

In addition, films were fabricated under various fragmentation patterns and the qualities of these films were evaluated. It was found that the film quality could be improved by dissociating SiH4 gas at low electron temperature.
Discoloration on color cathode ray tube and its correction system using L‐shaped magnetic material
Authors: Nasuno Hiroshi , Haga Akira
Published: July 2007

Color cathode ray tubes (CRTs) have been used as display devices for television sets and computers. Color CRTs contain a shadow mask to select electron beams for a particular color. The shadow mask is made of very thin (0.1 to 0.25 mm) iron and is easily magnetized. When the shadow mask is magnetized, the magnetic field profile in the CRT is modified, causing discoloration due to the deviation of electron beam trajectory.

To investigate the influence of the magnetization of the shadow mask on the electron trajectory, the magnetic characteristics of the shadow mask and its holder and magnetic field profile in the color CRT were analyzed using three‐dimensional magnetic field analysis. In addition, the influence of the magnetized shadow mask on the electron beam trajectory was calculated to find the quantity of mislanding. In this paper, the magnetic field control method by placing L‐shaped magnetic materials is proposed and it was proved experimentally that the correction of color discoloration can be achieved by this method.
Response of a dielectric sphere for electromagnetic pulsed wave—cases of back‐ and forward‐scattering
Authors: Itoh Akira , Hosono Toshio
Published: July 2007

It is important to analyze the scattering phenomena of a dielectric sphere in conjunction with the improvement of performance of weather radar to observe rain clouds. This paper considers the transient scattering phenomena when a plane electromagnetic pulse wave is incident on a dielectric sphere. Specifically, the responses of the back‐ and forward‐scattering observed at distant points are presented. The response waveforms are compared when the permittivity, loss, and incident waveform are varied. Analyzing the typical response waveforms, the propagation paths were estimated from the characteristics of the response time and waveform so that the scattering phenomena were studied. The fast inversion of Laplace transform (FILT) method was used for the calculation of the transient responses.
High‐power polymer optical fiber amplifier
Authors: Yamamoto Tsuyoshi , Fujii Kazuhito , Tagaya Akihiro , Teramoto Shigehiro , Nihei Eisuke , Koike Yasuhiro , Sasaki Keisuke
Published: July 2007

Organic dye‐doped polymer optical fiber amplifiers (POFA) are fabricated and their amplification characteristics are investigated. Rhodamine 6G, Rhodamine B, and Perylene Red are used as organic dyes for optical amplification. The amplification of optical signals at 571 nm, 591 nm, and 621 nm wavelengths is confirmed through pumping by the second harmonic of a pulse‐operated Nd: YAG laser. It is shown that very high output powers can be achieved by increasing the caliber of Rhodamine B doped POFA. One‐kW optical signal output (30 dB gain) is obtainable at dye doping of 1 ppm, 500‐μm core radius, and POFA length of 250 mm. The conversion efficiency of such a high output amplifier is 27 percent. The POFAs are advantageous over liquid‐dye lasers because they are easily handled. Multistage POFAs in the form of joint POFAs are proposed as new light source systems and their oscillation characteristics are discussed.
High‐power ALGaAs single‐stripe laser diode with window‐grown‐on‐facets
Authors: Matsumoto Mitsuhiro , Sasaki Kazuaki , Kondo Masaki , Takeoka Tadashi , Yamamoto Saburo , Ishizumi Takashi
Published: July 2007

A high‐power single‐stripe AlGaAs laser diode capable of reliable operation at an output power greater than 50 mW is useful for improvement in optical data storage systems and second harmonic generation elements. A novel window structure laser diode is developed and referred to as a window‐grown‐on‐facets (WGF) laser. Highly reliable operation is attained under 10 mW at 50°C beyond 10, 000 hours in the wavelength of 830 nm and under 70 mW at 60°C beyond 4000 hours in the wavelength of 780 nm, respectively. In the WGF laser, the window effects are found only in the case of the Al content of the window layer greater than that of the cladding layer. To explain the experimental results, calculation of carrier leakage from the active layer to the window layer is performed. The reduction of the window effects is caused by the carrier leakage.
Issues and perspectives in multilevel interconnection technology for quarter‐micron generation
Authors: Shibata Hideki
Published: July 2007

The size of elements in an integrated circuit has been reduced according to the proportional reduction scenario (scaling scenario) which has been essential in achieving high integration and high performance of Si ULSI.

In this paper, the issues and perspectives in reducing the dimensions of the interconnections will be reviewed. Then the influence of the RC delay caused by interconnection resistance and capacitance which are expected to be more serious in the quarter‐micron generation on the device performance will be discussed. In addition, a new scaling scenario needed to reduce the interconnection delay in accordance with the improvement of device performance will be proposed. At the same time, a way to improve interconnection reliability in high current density, planarization techniques, and self‐aligned techniques will be discussed.
An amorphous Ti‐Si‐N diffusion barrier layer for cu interconnections
Authors: Iijima Tadashi , Shimooka Yoshiaki , Suguro Kyoichi
Published: July 2007

This paper discusses the amorphous Ti‐Si‐N diffusion barrier layer without crystalline grain boundaries. The Ti‐Si‐N layers were sputter‐deposited in Ar‐N2 mixture gas using TiSi and TiSi2 targets. In particular, films with a composition of Ti: Si: N = 1: 1: 1.4 were evaluated. It was confirmed that the films were amorphous and thermally stable. The stress of the films was low and compressive, where it was 0.28 GPa. The junction leakage current measurement indicated that the barrier characteristic was effective at 600°C. Therefore, it was concluded that the amorphous Ti‐Si‐N layer could be used as a barrier for Cu interconnections.
Optimization of silicide process for sub‐0.1‐μm CMOS devices
Authors: Gotoh Ken‐Ichi , Fushida Atsuo , Yamazaki Tatsuya
Published: July 2007

A silicide process is indispensable to reduction of the parasitic resistance of deep submicron CMOS devices. The parasitic resistance degrades the operating speed of ultrafine gates, limiting development of further scale‐down CMOS devices. However, the conventional silicide process causes many problems, such as agglomeration, junction leakage and thermal instability, and cannot be used for mass production of deep submicron semiconductor devices. The limitations of conventional Ti, Pi, Ni, and Co silicide processes are investigated and analyzed, and it is found that a TiN‐capped Co silicide process is suitable for fabricating 0.1‐μm CMOS devices.
Development of a thermally controlled magnetization actuator (TCMA) for a micromachined motor
Authors: Hashimoto Etsu , Uenishi Yuji , Tanaka Hidenao , Watabe Akinori
Published: July 2007

The magnetization microactuator has several advantages including a long‐range operation and a self‐latching actuation which are not available in an electrostatic microactuator. However, the magnetic actuator using an electromagnetic coil is not suitable for micromachining due to its structural complexity. A new magnetic actuator (thermal magnetization‐controlled actuator) is proposed which does not require an electromagnetic coil due to the control of the magnetic force by heating the thermo‐sensitive magnetic material with a permanent magnet as the source of the magnetomotive force. The operating principle and the configuration are described. Further, a static torque was measured with a millimeter‐size torsional oscillator.

It was demonstrated that the static torque is reduced to less than 20 percent by thermomagnetic control so that more than 80 percent of the magnetic torque in the excited state can be used for torque generation. On the basis of this experimental result, the generated power of the thermally controlled magnetization actuator was discussed in comparison to the electromagnetically controlled actuator. It was demonstrated that the thermal magnetization control is an effective driving principle of micro‐machines.
Modeling and simulation of blanket chemical vapor deposition of WSix from WF6/Si2H6
Authors: Egashira Yasuyuki , Aita Hirofumi , Saito Takeyasu , Shimogaki Yukihiro , Komiyama Hiroshi , Sugawara Katsuro
Published: July 2007

The reaction mechanism of blanket chemical vapor deposition of WSix from WF6/Si2H6 mixture was modeled based on the data of a tubular reactor. In this reaction, film deposition is initiated by radical chain reaction and the silicon concentration in the film can be increased easily. The model is as follows. During radical chain reaction, reaction between WF6 and Si2H6 takes place, Si‐rich intermediary product with Si/W = 2 is formed and reaction between the product and Si2H6 causes an increase of Si concentration. The Si concentration profile in the film in the reactor could be simulated by using the reaction speed constant as a fitting parameter and the validity of this model was confirmed. The activation energy of this reaction was 23.5 kJ/mol. Using this model, the Si concentration in the film formed in the substrate‐heating‐type reactor could be predicted.
Degradation mechanism of contact resistance during window formation
Authors: Sekine Makoto , Kakuhara Yumi , Kikkawa Takamaro
Published: July 2007

This paper describes a contact degradation mechanism during window formation followed by selective tungsten chemical vapor deposition (W‐CVD). Contact resistances by using selective W‐CVD were increased as the overetching rate increased. Surface analysis made it clear that the Si surface at the bottom of contact was damaged and oxygen atoms from dielectrics were introduced during window etching. These damage and oxygen atoms break Si‐Si bonds and make Si‐O bonds after additional ion implantation. The Si‐O bonds degrade the valence‐band density of states of the Si surface. Such a damaged surface will not react with WF6. This inactivation is the reason for contact degradation. Controlling the Si surface state by using the chemical dry etching (CDE) technique solves this problem.
Lamé‐mode piezoelectric resonators using LiNbO3 crystals
Authors: Nakamura Kiyoshi , Kumasaka Katsunori
Published: July 2007

Piezoelectric resonators with a simple supporting feature have been in demand for numerous applications. In this paper, it is shown that the Lamé modes having vibration nodes at the four corners exist in a rectangular 155° rotated Y‐cut LiNbO3 plate with a length‐to‐width ratio of an integer number. The theoretical analysis of equivalent circuit parameters such as capacitance ratio, indicates that this mode can efficiently be excited piezo‐electrically. In addition, it is shown that the experimental results of the impedance characteristic, displacement distribution, and capacitance ratio of the Lamé mode resonators agree with the theoretical results. It is proved that the changes in the resonant frequency and the Q value due to the four corner supports are small.
Jitter stability in paired soliton transmission system
Authors: Sakai Atsumasa , Fujii Yoichi
Published: July 2007

The concept of diversity transmission was applied to the optical soliton communication system. For system configuration, two transmission lines are used and an optical coupler is inserted along the way. The configuration is resistant to Gordon‐Haus jitter caused mainly by the amplification spontaneous emission (ASE) noise from the optical amplifier. Using the present method, it shows that the timing jitter can be stabilized if the perturbation of the jitter is less than the width of the soliton pulse. It is also shown that the effect of the random phase variations received along the optical fiber transmission with a large effect of perturbation (such as the nonuniform distribution of the index of refraction) can be compensated. The paired soliton transmission system is the one for which a high transmission stability can be expected even in a transmission path with a large effect of the random jitter.
Fabrication of dispersive fibers and their application to long wavelength‐pass filters
Authors: Nishimura Junji , Ueda Yutaka , Morishita Katsumi
Published: July 2007

Dispersive fibers are fabricated in which the refractive index dispersions of the core and cladding cross at a certain wavelength. The core and cladding were made of different types of optical glasses. To pass a long wavelength light (to suppress short wavelength light), the refractive index of the core was chosen to be lower than that of the cladding in the short wavelength region. In the fabricated dispersive fibers, no waveguide mode was observed in the short wavelength region, indicating that the fibers play the role of a long wavelength pass filter. To evaluate the fibers as an optical filter, the transmission loss and insertion loss were investigated and it was found that the pass wavelength region could be controlled by changing the curvature of the fibers.
two‐dimensional transient analysis of in‐plane vibration in rectangular plates of piezoelectric ceramics
Authors: Sato Masahiro
Published: July 2007

In‐plane vibration in rectangular plates of piezoelectric ceramics which were polarized along the direction of plate thickness was investigated by two‐dimensional transient analysis. In this analysis, it was assumed that both the top and bottom surfaces of the rectangular ceramic plates were electroded entirely and the four‐edge surfaces were not constrained. The spatial network method was employed for numerical analyses. Transient responses were evaluated numerically first for the cases where stepwise input voltages were applied to square plates.

In‐plane wave motion and displacements of free edges were calculated. The results indicate the following behaviors: 1) a longitudinal wave is created at the free edge and propagates along the surface of the plate; 2) a part of the longitudinal wave is transformed to a shear wave at a free boundary parallel to the direction of the wave propagation; and 3) these two waves experience repeated reflections at the free boundaries and thus form a complicated vibration. Transient responses of a rectangular ceramic plate were analyzed next. Prior to the analysis, the vibratory behaviors of the rectangular plate were predicted approximately based on the results for the square plate. The detailed numerical analyses performed could confirm the validity of the predictions.
Low‐drive level characteristics of at‐cut resonators with cylindrical capsules
Authors: Momosaki Eishi , Oomura Yoshimasa
Published: July 2007

As a quartz resonator needed for miniaturizing electronic devices, a rectangular AT‐cut quartz resonator sealed in a cylindrical capsule has been developed and manufactured. It was found that the anomalous characteristics of the resonator at a low‐drive level have something to prevent starting oscillation. The drive level characteristics of the rectangular AT‐cut quartz resonator sealed in a cylindrical capsule have not been clarified to date. These characteristics are obtained from the low‐drive level to the high‐drive level. Among these characteristics, the anomalous phenomena at the low‐drive level (LDL) have been studied experimentally and theoretically. It was found that the anomalous phenomena are caused by the unwanted vibration of the structure other than the resonator plate itself. The frequency of the unwanted vibration depends strongly on the drive level. At the drive level that makes the frequency identical to that of the main resonance, an anomaly occurs in which the frequency and CI jump substantially. The manner of this jump can be calculated by assuming that the unwanted vibration is proportional to the current squared and the coefficient is large. The analysis shows a good agreement with the experimental result. In regard to the unwanted vibration found in the present experiment, it is assumed that the coefficient dependent on the square of the current of the unwanted vibration is negative and that the unwanted vibration is significantly originated in the structures attached to the quartz plate (such as electrodes, support member, mounting material, and dust).
Surface acoustic wave microsensors
Authors: Shiokawa Showko , Kondoh Jun
Published: July 2007

It was found that a surface acoustic wave microsensor is highly sensitive in detecting the physical and chemical changes of the medium on the vibrating surface in real time. Hence, microsensors are used in many applications. There are already several types of surface acoustic wave microsensors with their differences based on vibration and wave modes. New types of sensors are proposed herein and new findings and new applications are reported. The present level of development of surface acoustic wave microsensors is described and these sensors are compared, discussed, and evaluated.

Fundamental characteristics are then presented for the shear‐surface acoustic wave (SH‐SAW) microsensors using a 36° rotated Y‐plate X‐propagation LiTaO3 studied by the authors. It is shown that this sensor has many applications. Further, if several SH‐SAW sensors with different frequencies are used, a high recognition rate can be obtained even for liquid samples that cannot be recognized by human perception. The example used here is 13 types of whiskey.
Measuring system for photoresist development parameters
Authors: Sekiguchi Atsushi , Matsuzawa Toshiharu , Minami Youichi
Published: July 2007

To investigate the photoresist development characteristics, a development parameter extracting system for photoresists has been developed utilizing a development rate monitoring system and an exposure parameter measuring system for photoresists. This system is used to obtain the development parameters of a super‐high resolution i‐line photoresist, PFR‐ix500EL (Japan Synthetic Rubber Co., Ltd.), using the development rate equations by Dill, Kim, and Mack. At the same time, the dependence of the simulated profiles on the development rate equations is investigated. Focus latitude for achieving 0.5 μm lines and spaces under the conditions of exposure wavelength of 365 nm, NA = 0.5, and s̀ = 0.6 is evaluated; the simulated and experimental results are compared. It is found that when Mack's equation is used to simulate the development rate, the simulated and experimental results are in good agreement.
Three‐dimensional vector accelerometer using soi structure for high‐temperature use
Authors: Takao Hidekuni , Matsumoto Yoshinori , Ishida Makoto , Nakamura Tetsuro , Tanaka Hidekazu , Seo Hee‐Don
Published: July 2007

In order to improve the high‐temperature reliability of a silicon accelerometer, an accelerometer was fabricated using an SOI substrate and its temperature dependence was compared with that of conventional silicon accelerometers. In addition, the authors attempted to detect the three‐dimensional components of the acceleration vector using a new theoretical principle. The new theoretical principle was validated, and accelerometer design was carried out using a program for structure analysis, ANSYS, which is based on the finite element method (FEM). It was found that, in the accelerometer fabricated using an SOI substrate, the offset voltage and sensitivity at temperatures higher than 200 °C were superior to those in the conventional pn junction device. It was also found that the new device could detect acceleration even at 410°C. Using the new device, the acceleration components in the three directions were accurately measured and the sensitivity for the other axis was suppressed to less than 5.7 percent. The frequency characteristic of the new sensor was in agreement with the theoretical results. Because of high‐temperature operation and detectability of the three directional components of acceleration, this new accelerometer will be much more widely used.
Liquid‐crystal display cell model using piecewise approximations
Authors: Shima Takeshi , Okumura Makiko , Higuchi Toyoki
Published: July 2007

The dynamic characteristics of the capacitance of liquid‐crystal display (LCD) pixel constituting the active matrix LCD device using amorphous thin film transistors (TFTs) have been analyzed; an electrically equivalent circuit model is proposed based on the obtained results. The model consists of nonlinear resistors and dynamic elements such as capacitors or inductors and can represent the voltage and time dependence of the capacitance value in the LCD pixel. The proposed model is incorporated into the circuit simulator SPICE as a built‐in model.
Method of detecting a specific ion by means of crown ethers
Authors: Hirakawa Hiromitsu
Published: July 2007

To replace the conventional ion‐sensitive field‐effect transistor (ISFET) ion sensor, an ion‐sensing method using crown ether was developed. In this method, the alkaline metal ions (Na+ and K+ ions) were detected by the ac potential difference. Crown ether shows selectivity toward alkaline metal ions, forming complexes.

To investigate the selective characteristics of crown ethers using the ac potential difference, three types of crown ethers (18C6, 15C5, and 12C4) were used. The solvents used were water, methyl alcohol, acetone, propylene‐carbonate (PC), and dimethyl‐formamide (DMF). Specifically, chlorides (NaCl, KCl, and CsCl) were dissolved in the solvent containing crown ether and the sedimentation potential was measured using a sedimentation‐potential measurement system.

When 18C6 was used, the highest sedimentation potential of KCl was observed if PC was chosen for the solvent. When 15C5 was used, the highest sedimentation potential of NaCl was observed if methyl alcohol was used for the solvent. It was confirmed that in order to distinguish K+ and Na+ ions from other ions, PC containing 18C6 and methyl alcohol containing 15C5 should be used, respectively.
A high‐speed 4‐Gsample/s 2‐bit ADC system for radio astronomy
Authors: Matsumoto Kin'Ya , Kawaguchi Noriyuki , Horiuchi Kenji
Published: July 2007

In recent years, the use of very long baseline interferometer (VLBI) devices has increased in the geodesy and radio astronomy communities. To enable these devices to pick out very small variations, it is desirable to increase the sensitivity of the detection of the VLBI. For observing quasars, it is beneficial to increase the observation bandwidth and improve the sensitivity of detection. However, for such wide bandwidth systems, gigahertz‐order sampling high‐speed A/D converters are necessary and the technology for achieving these devices is not yet developed. In this work, we developed, using Si‐bipolar LSI processes (SST‐1B), a 4‐Gsample/s 2‐bit ADC LSI and created a high‐speed ADC system. We evaluated the loss in this system due to phase stability, sampling jitter, and the uncertainty region of the comparator of the LSI to evaluate the coherence of the VLBI. We used a frequency transformer device and a picosecond phase comparator as the measurement device for measuring the phase stability of the gigahertz‐order ADC system. From the measurement results, we determined that the Allen standard deviation over 1‐s of integration time was 3.6 × 10−13, the sampling jitter was 13.4 ps, and the comparator uncertainty was 20 mV. For a wide bandwidth burst mode VLBI observation system with an observation frequency of 230 GHz, a coherence loss of 7.6 percent was observed. We then demonstrated the operation of the ADC system by detecting real radio astronomical observation spectra using this device.
An analysis of the resonance frequencies of stepped, clamped‐free torsional mode resonators and their applications to quartz crystal tuning fork
Authors: Kawashima Hirofumi
Published: July 2007

This paper describes torsional mode quartz crystal resonators of the tuning fork type with stepped vibration bars. A frequency equation and a transcendental equation were derived from the “clamped‐free” boundary condition and the stepped portion of the continuity condition, respectively. Because these equations were given as a function of torsional rigidity, the torsional rigidity was derived from the equation of equilibrium. From related equations, it was shown that high or low frequency could be obtained without a change in length. The calculated results were then compared with the measured values so that both results would be in good agreement.
Integrated optic micropressure sensor using ring resonator
Authors: Ohkawa Masashi , Abe Tetsuharu , Sekine Seishi , Sato Takashi
Published: July 2007

In this paper, sensitivity improvement of integrated optic micropressure sensors is discussed. The sensor is composed of a diaphragm and a ring resonator that is a multiple interference optical circuit. A part of the waveguide of the ring resonator is on the diaphragm. When a pressure is applied to the sensor, the diaphragm is deformed and the refractive index changes slightly so that a phase shift is induced on the guided wave propagating on the diaphragm. From the change of the resonant frequency caused by this phase change, the magnitude of the applied pressure is detected. In this study, particular emphasis is on the relationship between the diaphragm dimensions and the sensor sensitivity. From the analysis of the sensor operation, it is concluded that the use of a square‐shaped diaphragm with a waveguide of the ring resonator at the edge in addition to employing the TM‐like mode is most suited for a highly sensitive sensor. Further, from the evaluation of the minimum detectable pressure, it is expected that an integrated optic microprocessor sensor can be realized which is sensitive to such low pressure as underwater acoustics.
Improved operation of logic devices constructed by asymmetric nonlinear optical fiber couplers using bandwidth limited amplification
Authors: Kojima Takashi , Koshiba Masanori , Tsuji Yasuhide , Eguchi Masashi
Published: July 2007

Effects of perturbations including third‐order dispersion on the operation of logic devices constructed by asymmetric nonlinear optical fiber couplers are investigated by using the beam propagation method. In contrast to the unperturbed case, the radiation is stimulated and, consequently, the operation of logic devices is degraded. In order to remove the influence of perturbations, the bandwidth limited amplification is introduced. In a distributed gain medium with a finite bandwidth, the radiation caused by third‐order dispersion may be suppressed and the operation of logic devices is improved.
Analysis of a novel intersection waveguide‐type optical polarization splitter using birefringence of GaInAsP/InP superlattice
Authors: Kambayashi Toshio , Nakasendou Kazuyuki
Published: July 2007

A novel intersection waveguide‐type polarization splitter based on total reflection using the birefringence of the GaInAsP/InP superlattice waveguide is proposed and analyzed in this paper. The semivectorial finite difference beam propagation method (FD‐BPM) (which handles both TE and TM modes) is used in the analysis. The waveguide structure including the GaInAsP/InP superlattice is designed; and it is shown that, although with a superlattice core the refractive index for the TM mode is reduced by approximately 0.4 percent, there is no change for the TE mode. Based on this result, the optimal structural parameters such as superlattice layer number, rib height (h), intersecting angle (θ), and port separation length (Lsp) are investigated using a 1.55μm wavelength. It is found that the TE and TM modes can be separated with an insertion loss of less than 0.4 dB for both modes and a crosstalk of less than −35 dB using an intersecting angle of 5° and a device length of approximately 0.9 mm. It is shown that compared to conventional devices, the device length in the proposed device structure can be reduced by using total reflection. The wavelength dependence of the device is also analyzed.
Precise measurement of resonance current and frequency characteristics of quartz oscillators for oven‐controlled crystal oscillators
Authors: Koyama Mitsuaki , Watanabe Yasuaki , Sekimoto Hitoshi , Oomura Yoshimasa
Published: July 2007

This paper presents a precise measurement method for obtaining the drive power dependency of frequency in highly stabilized quartz‐crystal oscillators. The method is aimed at improving the frequency stability of crystal oscillators and, in particular, oven‐controlled crystal oscillators (OCXOs). It uses a transistor Colpitts oscillation circuit which features excellent resolution and reproducibility of electrical current measurements as well as higher operating frequencies than those of conventional techniques such as transmission or reflection methods. In this paper, the authors demonstrated concepts of this method and a corresponding measurement system. The proposed method also was applied to SC‐cut crystal oscillators used in OCXOs which had shown nonsatisfactory frequency stability (discussed earlier by the authors). Here, the authors demonstrated that those problems were caused by frequency jumps in the oscillator frequency‐versus‐current characteristic. It was shown also that OCXO circuits with excellent reproducibility of temperature characteristics can be implemented by using an appropriate level of driving current to drive the quartz oscillator in the generation mode.
MgO powders for protective layer of alternating current plasma display panel
Authors: Koiwa Ichiro , Kanehara Takao , Mita Juro , Ono Sachiko , Osaka Tetsuya
Published: July 2007

The MgO powder used for a screen‐printed protective layer on plasma display panels was evaluated. The MgO powder was formed by either vapor‐phase oxidation or decomposition of Mg(OH)2. For the same BET value, the diameter of MgO particles formed by the latter method was larger than that by the former method. It was found that the particle diameter calculated by Scherrer's equation using the half‐value width of an X‐ray diffraction pattern was less than one‐fifth of that calculated using the BET value. When the distribution of the particle size was evaluated by the centrifuge precipitation method, it was found that both the median and modal diameters of the MgO powders formed by the latter method were larger than that by the former method. The powder formed by the latter method also contained powder with diameters of less than 20 nm; the weight ratio of the fine powder to the entire MgO powder was 5.5 ∼15.9 wt%. The transmission electron microscopy (TEM) observation revealed that the powder formed by the former method had a higher crystallinity and that the powder formed by the latter method tended to aggregate. When protective MgO layers were fabricated by sintering MgO powder formed by the above two methods, the powders oriented in the (111) orientation and the MgO formed by the former method had a higher crystallinity. It was concluded that, since the MgO powder formed by the former method (vapor phase method) had a finer particle diameter, higher crystallinity, and higher uniformity than the powder formed by the latter method (decomposition of Mg(OH)2), the MgO powder formed by the former method is more suitable for the alternating current plasma display panel (AC‐PDP) printed protective layer.
Soliton system evaluations using fibers with dispersion and loss fluctuations
Authors: Ishiba Kazuo , Komatsu Tadayoshi , Takahara Mikio
Published: July 2007

In the development of practical multimedia systems, greater capacity is desired in a long‐distance large‐capacity transmission system. A number of studies have been undertaken to develop a long‐distance large‐capacity system. Several long‐distance transmission experiments for high‐density transmission by wavelength demultiplexing method (WDM) have been reported recently. However, more of the experimental examples have reported on soliton transmission than on WDM systems. Hence, the former is considered more advanced. It is necessary to prepare a fiber of a length of approximately 10, 000 km for ultralong‐distance transmission experiment. Since this is difficult to obtain, repetitive experiments are often the case. However, such an experiment does not disclose the effects of dispersion and loss fluctuation in the fiber. In this paper, the effect of fluctuation in dispersion and loss in the fiber is studied by simulation so that the resilience of the soliton to the variations of the fiber characteristics is evaluated.