bluuebunny/crossref_metadata_2025 huggingface dataset:
A simple measurement technique for the refractive‐index change caused by the thermooptic effect
Authors: Kishioka Kiyoshi
Published: July 2007

When a thin metallic film electrode deposited on the surface of a glass substrate is heated, a change is produced in the refractive index due to the thermooptic effect in the substrate, which is proportional to the temperature distribution. Due to the gradient of the refractive index produced below the electrode, the laser beam passing through the substrate is deflected toward the electrode. This paper presents a simple technique for the measurement of the refractive‐index change below the electrode, which utilizes the deflection of laser beam. The method is applied to fused silica, Pyrex glass, Tempax glass and B‐270 glass and the measured results are shown. Together with the increment of the refractive index, a constant determining the temperature distribution of the substrate and the temperature of the electrode are also measured. To verify the validity of the method, the thermal coefficient representing the temperature dependence of the refractive index is calculated from the measured refractive‐index increment and the electrode temperature. The result for the fused silica is compared with the previously reported value. As a result, it is seen that the value obtained by the proposed method agrees well with the published value. A discussion is also made on the accuracy of the measured values.
Surface acoustic wave convolver using multiple waveguide
Authors: Nakagawa Yasuhiko , Makio Satoshi
Published: July 2007

A new elastic convolver is proposed in which a nonlinear interaction of surface acoustic waves (SAW) on multiple waveguides is used. Theoretical and experimental investigations are carried out. When two SAWs with angular frequency of ω and wavenumber of β, and with ω and‐β propagate in opposite directions on N waveguides, the parametric mixing phenomenon generates a SAW with a sum frequency traveling in the direction normal to the waveguide. The generation efficiency increases: (i) when the width of one of the waveguides is one‐half the wavelength of the sum frequency SAW; (ii) with the number N of the waveguides with the maximum occurring at N = 8 ∼ 10; and (iii) with the larger velocity difference (ΔV/V). Generation of the sum frequency SAW is possible only with the guided mode of SAW. The present convolver can be matched easily with the external circuit, because the convolution output is extracted with an interdigital electrode (IDT).
Automating inspection of aluminum circuit pattern of LSI wafers
Authors: Hara Yasuhiko , Fushimi Satoru , Ooshima Yoshimasa , Kubota Hitoshi
Published: July 2007

An automatic inspection method of defects of aluminum‐circuit patterns (cuts, short‐circuits and other irregularities) formed on the top layer of multiple‐layer LSI wafers was studied. The defects in question are irregularities greater than half the pattern width, since the aluminum‐circuit patterns have relatively large irregularities along the boundaries of the patterns, and it is not necessary to detect them as defects.

The wafers have multiple‐layer patterns consisting of aluminum and polysilicon, etc., and it is generally difficult to distinguish the aluminum‐circuit patterns alone from others. We found a method of detecting aluminum‐circuit pattern clearly by using bright‐field and dark‐field illumination (an illumination from a diagonal direction) simultaneously, and by making the intensity of the latter stronger. A method of detecting defects of a pattern was also examined in which a pair of patterns is compared and their mismatching is regarded as a defect. A pattern‐matching error‐detection method was developed. In this method, a position of patterns which makes the integration of the logic exclusive‐or sum minimum is measured in real time. A method of aligning a pair of patterns was also developed. The detection of defects having the size of 1 μm (3 pixels) was achieved by detecting a mismatching part of asymmetrical shapes in the two patterns which are aligned.
Wavelength stabilization of a semiconductor laser in high‐speed modulation using the Rb‐D2 absorption line
Authors: Sato Takashi , Sugai Hiroyuki , Shimba Minoru
Published: July 2007

The wavelength stabilization of a semiconductor laser under high‐speed modulation is reported. The applied stabilization method uses the difference between an atomic absorption line and oscillation wavelength as a feedback signal. In this paper, this method was applied under high‐speed modulation. The broadening of the oscillation wavelength width by generated sidebands under high‐speed modulation distorts the feedback signal and degrades the stability. However, the wavelength stability (Allan variance) 10−10 ∼ 10−8 was obtained by using the Rb D2 absorption line under the modulation frequence 50 to 200 MHz and the modulation current smaller than 1.6 mAp‐p.
Phase matched SHG of surface polariton along a silver layer on a slab‐type optical waveguide
Authors: Sasaki Keisuke , Kawagishi Hideyuki , Ishijima Yoshihiro
Published: July 2007

The existence is found for coupled guidedand surface polariton‐modes, in a slab‐type waveguide with a silver thin layer on top of it. The phase‐matched condition for the second harmonic generation (SHG), due to the fundamental and surface polariton modes, is determined. In waveguides of this structure, the realization of long propagation‐length (i.e., long interaction‐length) is possible in a waveguide with energy storage (Corning glass 7059), to compensate for the losses due to excitation of plasma polaritons. The generation of the phase matched second harmonics due to the surface polaritons is experimentally observed. The waveguide is tapered perpendicular to the direction of propagation. The theoretical phase matched condition between the fundamental and second harmonic waves is determined for a specific silver thickness on top of the slab waveguide. This phase‐matched condition is confirmed experimentally. The output of a Q switched Nd: YAG laser is used as the fundamental wave.
I‐V characteristics of photodetector using the GaAs MESFET
Authors: Umeda Tokuo , Cho Yoshio
Published: July 2007

The experimental results of the optical response characteristics of GaAs MESFET photodetectors were analyzed numerically, using the optical response mechanism of the FET. The device used was designed for the X‐band applications and the numerical analysis was carried out mainly on the IV characteristics. As a result, the experimental results were explained successfully by taking into account the influence of the optically controlled channel current.
Finite‐element analysis of dielectric slab waveguide with finite periodic corrugation
Authors: Hirayama Koichi , Koshiba Masanori , Suzuki Michio
Published: July 2007

To calculate the reflection/transmission characteristics of a dielectric slab waveguide with finite periodic corrugation, a numerical approach based on the finite‐element method is proposed. Although the finite‐element method has already been applied to discontinuity problems in dielectric waveguides, it was virtually impossible from the viewpoints of computation time and computer capacity to apply the finite‐element method directly to a waveguide with many discontinuities such as a finite periodic waveguide. In the present article, a “substructure” has been introduced to the finite‐element formulation to treat a large number of discontinuities. Consequently, the interaction of surface waves and radiated waves among all discontinuities is automatically taken into account. Also, an unbounded waveguide is replaced by a corresponding bounded one; this creates a problem where an artificial boundary should be set. It was found that in a finite periodic waveguide, a good approximate solution can be obtained by choosing the position of the artificial boundary with an adequate distance from the waveguide, since the dependence of the solution on the position of the artificial boundary is not significant. The validity and usefulness of this method was confirmed by comparing the numerical results with the values obtained from other theoretical methods and the experimental values.
A study on error rate monitoring in mobile satellite communication systems
Authors: Sakai Tsutomu , Nakajima Shigeo , Mishima Hiraku
Published: July 2007

Mobile satellite communication systems employ the wide area accessibility of a satellite. Digital signal transmission systems which enable communication by highly efficient voice encoding techniques and error correcting techniques, even on low C/N channels, are being studied and developed in many countries. This paper studies error rate monitoring for application to antenna tracking control and transmitting power control in mobile satellite communication systems. A soft decision error correction method, which is expected to be available in a wide range of C/N, is proposed and its performance is clarified theoretically and experimentally. Considering the application to ship antenna tracking control, the monitoring accuracy on fading channels is evaluated experimentally. A simulation experiment is carried out for an electronic tracking control with switching arrays, and the reception level degradation due to tracking error is clarified. Simulation results of transmitting power control against rain attenuation are also given.
A low‐drift DC amplifier utilizing thermal feedback
Authors: Lino Shoichi , Sanada Toru , Hashiguchi Sumihisa
Published: July 2007

In electronic measurement, industrial measurement, medical instrumentation and industrial control, there are several practical problems in dc amplifier characteristics such as initial offset voltage, temperature drift, time drift, noise and input bias current. In some applications, a dc amplifier with a good long‐term stability is required. This paper presents a method for realizing a dc amplifier suitable to these applications. After characteristics of the components used are matched as much as possible, a thermal feedback is introduced that suppresses the effect of the ambient temperature fluctuation. First, a model of the system is introduced and the thermal coupling stage of the first stage affecting the drift is analyzed so that the parameters necessary for suppression of the temperature drift are obtained. Next, this model is used for derivation of the degree of suppression of the drift by the present method. A method of selecting the parameters and a design procedure are discussed. It is found that the temperature drift can be suppressed by 40 dB at an extremely low‐frequency range in the test amplifier and the temperature coefficient is 0.36 μV/°C. At specific frequencies, the improvement is 16 dB at 0.27 mHz and 10 dB at 0.6 mHz.
Finite–element method analysis of microwave and optical waveguides—trends in countermeasures to spurious solutions
Authors: Koshiba Masanori , Hayata Kazuya , Suzuki Michio
Published: July 2007

This paper presents a review of finite‐element methods for the analysis of microwave and optical waveguides, particularly focusing on the recent results for suppressing or eliminating techniques of the spurious solutions that have become a subject of discussion to date. The finite‐element method analysis of electromagnetic waveguides can be divided into four classes: (1) scalar wave analysis by the one‐dimensional finite‐element method; (2) vectorial wave analysis by the one‐dimensional finite‐element method; (3) scalar wave analysis by the two‐dimensional finite‐element method; and (4) vectorial wave analysis by the two‐dimensional finite‐element method. Spurious solutions appear in (4), and, depending on the variational expression used, they also appear in (2). Placing emphasis on (2) and (4), particularly on (4), various finite‐element formulations are presented such as axial fields of E and H, full vector H field, full vector E field, transverse fields of E and H, and transverse fields of E or H formulations, and various approaches capable of suppressing or eliminating the spurious solutions are reviewed in detail.
Design method for triple–clad silica core optical fibers with zero total dispersion at wavelengths of 1.3 and 1.55 μm
Authors: Furukawa Shinichi , Nakazawa Kazushige , Hinata Takashi , Hosono Toshio
Published: July 2007

This paper describes the design method for triple‐clad silica core optical fibers with zero total dispersion at wavelengths of 1.3 and 1.55 μm; (ac, Sc) is the point where the total dispersion (= S) at wavelengths of 1.3 μm becomes equal to that at 1.55 μm when the core radius (= a) is varied. We denote the relative index difference between the core and the mth clad at 1.55 μm by Δm+1 (> 0, m × 1, 2, 3), the thickness of the mth clad by tm (m × 1, 2, 3), the cut‐off wave length for the second mode by λc and the equivalent bending radius (= radius where the bending loss is 0.01 dB/km as R. The following conclusions have been obtained: (1) even if the conditions for the zero dispersion are satisfied in an ideal triple clad (TC type), the zero dispersion condition cannot be satisfied when fluctuations and round shoulders happen to exist in the clad layers (nonideal TC type); (2) to fabricate fibers of TC type and nonideal TC type with |Sc| < 0.1 ps/km/nm, λc ≤ 1.15 μm and R < 5 cm. The following conditions should be satisfied: Δ2 = 2Δ4, Δ3 ≤ Δ4, Δ4 ≥ 0.7% and t1/ac ≤ 1.04 for t2/t1 × 0.5; (3) if the item (2) is satisfied, the sensitivities of Sc to ac, Δ2, and Δ3 for wavelength of 1.3 μm are constant when t1/ac ≤ 2.0. However, at wavelength of 1.55 μm, they decrease as t1/ac decreases; and (4) R for wavelength of 1.55 μm is about 10 times larger than R for wavelength of 1.3 μm.

In this paper, the total dispersion is computed by the differentiation formula for determinant. Therefore the significant digits of the total dispersion in our results are more than four.
DC–coupled broadband and gain controllable monolithic amplifier circuits
Authors: Ishihara Noboru , Akazawa Yukio , Konaka Shinsuke , Kawarada Kuniyasu
Published: July 2007

This paper will describe a method for broadening the bandwidth of gain controllable monolithic amplifier circuits for the purpose of the application to the repeater circuits in the Gb/s optical transmission systems. The gain controllable differential amplifier circuit exhibits narrower bandwidth because of larger parasitic capacitance components in comparison with basic differential amplifier circuits due to the complicated circuit configuration to control the gain. Also, when the peaking method for broadening the bandwidth is applied, the peaking amounts exceed the optimum value and becomes unstable in the low‐gain operation even if the peaking amounts are optimized for the high‐gain operations. In this paper, a new gain controllable amplifier circuit using the bias current dependency of differential resistance of diodes is proposed. Furthermore, the circuit is fabricated by using the Si Bipolar Super Self‐Aligned process Technology (SST). A broadband characteristic of 1.6 GHz bandwidth and 29‐dB gain controllable width has been obtained. These are sufficient for the application to the Gb/s optical repeater circuits.
Nonlinear susceptibility of cesium and sodium atoms for frequency upconversion from 10‐μm atmospheric window to the visible
Authors: Mishima Teruhito , Hisadome Kenji , Members Ichiro Sakuraba,
Published: July 2007

This paper presents a calculation of the third‐order nonlinear susceptibility for the frequency upconversion of 10‐μm atmospheric window to the visible band. The following cases are compared.

Two‐photon resonance 1 at 6 d 2D3/2, and 2 at 6 d 2D5/2 of cesium to generate difference frequency. 3 Two‐photon resonance at 7 s 2S1/2 of cesium to generate sum frequency. 4 Two‐photon resonance at 3 d 2D5/2 of sodium to generate sum frequency. Density matrix is used in the calculation, and the spinorbit coupling and the Doppler effect are considered. The major results are the following. In 1, a large nonlinear susceptibility and large number density is obtained at relatively low temperature. The nonlinear susceptibility has the maximum at the wavelength of 12.1 μm. In 2, a large nonlinear susceptibility and large number density are obtained at relatively low temperature. The nonlinear susceptibility increases with the increase of infrared wavelength. In 3, a system free from polarization property can be constructed, but the temperature must be raised by more than 100°C, compared with the forementioned two cases. In 4 the largest nonlinear susceptibility is obtained for the wavelength of 9.1 μm. However, the temperature must be raised by several hundreds degree compared with the cases of 1 and 2.
Analysis of remotely sensed image data by means of category decomposition
Authors: Member Minoru Inamura,
Published: July 2007

The pattern recognition of a spectral characteristic which is the same method as the latter recognition, is one of the most widely used in remotely sensed multispectral image processing. There are many pixels in remotely sensed image data in which multiple categories are mixed within an instantaneous field of view. This paper points out that a conventional category classification in which the generalized distance of a feature space is used as the evaluation standard of the similarity is not necessarily suitable for the contents of pixels in remotely sensed image data. Also, it is more logical to use a method based on the calculation of the areaoccupation rate (the mixture ratio) of each category. From the viewpoint of the composition and decomposition of the categories, the generalized inverse matrices, least‐square, and quadratic programming were reexamined, and they are compared with conventional methods by using numerical examples. The results confirm the usefulness of the categorydecomposition method and problems of the conventional category‐classification methods including the maximum‐likelihood method (i.e., misclassification of pixels containing multiple categories). As a conclusion, if a more accurate calculation of the mixture ratio becomes available by a further development of the method, a higher order of information than that by a conventional categoryclassification processing applied to the image data on the earth surface will be obtained; it will even be possible to exceed the limit of the space‐resolution of a remote sensor.
Growth and evaluation of large KDP Single Crystals for High–power harmonic generation by temperature decrease method
Authors: Shimomura Osamu
Published: July 2007

In the growth of KDP single crystals by the temperature decrease method, the dimensions of equipment for the growth of the crystal whose dimensions are desired for type I and type II phase matching of SHG are discussed, where the (001) plate and (101) plate are used as seed crystals, respectively. It is shown that the equipment has the smallest dimensions in the growth of the crystals for type II with the seeds of the (101) plate. Then the large crystals are grown with the seeds of the (101) plate and their optical characteristics are described.
A Phenomenological consideration on E x B discharges
Authors: Tanizuka Noboru
Published: July 2007

Because of the varieties and the potentialities in technological and scientific applications of E x B type discharges, a systematic theory to interpret phenomena occurring there must be developed. This paper proposes to develop a theory of a small fluctuating electric field by which the electric field of the crossed field system is superposed. The resonance between the fluctuation and the motion of ions confined in the field system induces a convergence to a component of the ionic motion. As a result, under a certain condition, the chaotic ions in the field system form spokes. These phenomena (spoke formation process and spoke rotation) observed in E x B devices are interpreted by comparing the theoretical results.
Characteristics of Leaky Surface Acoustic Waves on LiNbO3 and the New Cut
Authors: Shimizu Yasutaka , Murakami Kyoji
Published: July 2007

Recently, surface acoustic wave devices have been used in many fields, for example as filters and so forth. However, since the device characteristics are determined by the substrate, the superior substrate for surface acoustic wave applications has been investigated. In this study, the leaky surface acoustic wave propagating in LiNbO3 has been evaluated theoretically and experimentally. First, the contour maps of the characteristics have been obtained for an arbitrary cut, and the propagation characteristics of the leaky surface acoustic wave in the LiNbO3 have been investigated. As a result, the standard for the substrate selection has been established. It was proven theoretically and experimentally that the proper selection of the cut could provide both the high electrical‐mechanical coupling coefficient (15%) and such excellent thermal characteristics as zero temperature coefficient which could not be obtained by conventional devices using Rayleigh wave propagation. As a result, a large electrical‐mechanical coupling (13.1%) which agreed with the theoretical value, has been obtained and the thermal characteristic (50 ppm/°C), much superior to that of conventional devices, has been obtained.
Inverse scattering method for one‐dimensional inhomogeneous lossy medium using linear prediction method
Authors: Watanabe Hideaki , Uehara Yoshiyuki , Noguchi Akira
Published: July 2007

A method of solution based on a linear prediction method is presented for an inverse scattering problem in which the permittivity ε(x) and the conductivity s̀(x) in a one‐dimensional inhomogeneous lossy material are estimated from the reflected and transmitted waves. The present method is shown in the following manner. First, from Maxwell's equation governing the medium, coupled equations for the forward and backward waves are derived which subsequently are discretized. In the discretized coupled equations, the permittivity ε(x) and the conductivity s̀(x) are included as coupling potentials. Also, if these discretized coupled equations are used, the transmitted and reflected waves for the incident impulse are an AR and an ARMA process, respectively. Their AR and MA parameters are closely related to the coupling potentials. Hence, from the reflected and transmitted waves for the incident impulse, the permittivity and permeability of the medium can be determined via the coupling potentials. To confirm the validity of the forementioned method, several computer simulations have been carried out.
A high‐speed SRAM using BICMOS technology
Authors: Douseki Takakuni , Ohmori Yasuo
Published: July 2007

To realize a large‐capacity, high‐speed ECL‐compatible SRAM with an access time comparable to that of bipolar ECL RAMs, we have investigated a circuit configuration and optimizing method for SRAMs with peripheral circuits consisting of BiCMOS circuitry except for memory cells on the basis of submicron BiCMOS technology. A predecoder configuration with a bipolar small‐amplitude logic circuitry is proposed and the number of predecoders that minimizes the decoder power dissipation is determined. Also, a word‐driver circuit that utilizes an NMOS transistor as the driving transistor with BiCMOS inverters is proposed, and its highspeed operation is confirmed. Next, a multiplexer which selects a pair of bit‐lines by switching the pull‐up voltage with an NMOS transistor and drives data‐lines with emitter‐follower circuits is proposed and its high‐speed operation confirmed. Finally, an optimized memory cell array configuration that minimizes the delay time from the memory cell to the multiplexer is proposed.
Evaluation of mode‐field‐diameter definitions and conditions for single‐mode fibers by transmitted field pattern methods
Authors: Kuwaki Nobuo , Ohashi Masaharu , Tanaka Chihaya , Uesugi Naoshi
Published: July 2007

This paper investigates the relative effectiveness of three different definitions of mode‐field diameter in evaluation of splice losses of current and dispersion‐shifted fibers. As a result, it is shown that the difference in splice losses, due to various definitions, increases with decreasing V value. Further, it is confirmed theoretically and experimentally that by using Petermann's new definition, it is possible to estimate the splice loss very well. Next, using NFP and FFP methods, the measurement conditions of mode field diameter are also investigated. As a result, it is shown theoretically and experimentally that to keep the measurement error below 1 percent, it is necessary for the dynamic ranges of NFP and FFP methods to be larger than 25 and 35 dB, respectively. Under these conditions, it is shown that the measured results of both methods are in good agreement.
Elliptical micro‐fresnel lenses fabricated by electron‐beam writing technique
Authors: Shiono Teruhiro , Setsune Kentaro , Yamazaki Osamu
Published: July 2007

Elliptical micro‐Fresnel lenses can exhibit astigmatic characteristics; and hence, an astigmatic optical system made of a conventional combination lens can be made much thinner by their use. The authors have developed an electron‐beam writing system which has a function suitable for fabrication of thin‐film micro‐optical elements. The function of this writing system has been expanded so that elliptical micro‐Fresnel lenses can be fabricated. It has been confirmed that the fabricated lenses have a good sawtooth cross section. For the focusing characteristics of the lens, the eccentric ratios and the observation position dependence have been investigated theoretically and experimentally. The obtained focused spots almost reach the theoretical diffraction limit in both the major and minor directions. The intensity distribution of the focusing spots agree with the theoretical prediction. Hence, the fabricated lenses have focusing characteristics in agreement with the designed ones. Compared to the conventional microlens, these elliptical Fresnel lenses have a size smaller by one order of magnitude and their focusing efficiency is as high as 72 percent. Hence, it is expected that these lenses are new elements for micro‐optics.
Conduction mechanism of polycrystalline silicon thin‐film transistors
Authors: Saito Yoji , Abe Kazuhiko , Kawamoto Chinami , Kuwano Hiroshi
Published: July 2007

The drain current in polycrystalline silicon (polysilicon) TFTs (Thin Film Transistors) increases with increase of the gate voltage even if the polarity of the gate voltage is opposite to that of the drain voltage. This behavior is different from that in single‐crystal silicon MOSFET's. In this paper, to clarify the mechanism of this drain current, the dependence of the reverse bias current of polysilicon p+in+ diode with an MOS gate on voltage and temperature is examined. As a result, it is found that the mechanism of this current is Poole‐Frenkel current. Moreover, a simple model to explain the voltage and temperature dependence of this drain current is proposed, and its propriety is shown.
Relation between the loading characteristics and the mutual synchronization characteristics of microwave oscillators
Authors: Fukumoto Katsumi , Nakajima Masamitsu
Published: July 2007

The mutual synchronization characteristics at microwave frequencies have been studied from a practical viewpoint to combine the outputs from several oscillators and obtain a high power. However, in most of the studies, Van der Pol oscillators are used as a model of the oscillator. It is well known that the experimental results of the injection locking characteristics of Van der Pol oscillators cannot be predicted accurately as the injection signal becomes larger. In the previous report, an oscillator model was proposed with which the load characteristics of the microwave oscillator are expressed much more accurately. It was demonstrated that the analysis on the injection locking characteristics based on this model agree well with experimental data. In this paper, a new oscillator model is used and a quantity called the degree of coupling between the oscillator and the transmission line is introduced. In the system in which the oscillators are coupled with frequency‐dependent transmission lines, the effect of the oscillator coupling system on the synchronization characteristics is investigated. The circuit condition for power combining is found. Good agreement with the experimental results is confirmed.
A measurement and a classification of arcing phenomena of AgPd alloy contacts in low pressure
Authors: Sone Hideaki , Takagi Tasuku
Published: July 2007

To understand the arcing phenomena observed when contact is breaking, an apparatus was developed to observe and record arc voltage waveforms. The apparatus is formed by adding a waveform acquisition circuit composed of an A/D converter, memories and control circuits to the conventional contact measurement system. Using this equipment, the voltage waveforms were observed for Ag, Pd or their alloys contacts for 500 operations under various surrounding ambient pressures. The waveforms were analyzed with respect to length, slope and fluctuation. The waveform tendencies were classified by the combination of ambient pressure and alloy ratio. For example, when the Ag content is high or the ambient pressure is high, the transition to gaseous phase becomes smoother with the increase of operation repetitions. When the Pd content increases and the ambient pressure is low, only a short metallic phase arc occurs. Using the measurement and classification, data for establishing the relationship between the ambient pressure and the contact material was acquired. The classification carried out by using contact resistance was similar to that by arc waveforms.
Direct core observation method using thermal radiation of silica fibers with dopants
Authors: Katagiri Toshiaki , Tachikura Masao , Ishihara Koushi
Published: July 2007

Various direct core observation methods have been developed for directly observing the core itself of a single‐mode optical fiber such that the axial alignment is performed and the splicing loss can be evaluated. In the conventional methods, special devices are needed such as an He‐Cd laser and a collimated illuminating optical source. In this paper, the optical fiber core can be observed directly by thermal radiation when Ge‐doped optical fibers are spliced by glow discharge heating. Also, this phenomenon can be used for splicing. When a Ge‐doped fiber is placed near the glow discharge heating region, the core shines in contrast to the clad. This is because the absorbing loss of the core is larger than that of the clad and hence a stronger thermal radiation occurs from the core. Further, near the wavelength of 420 nm, Ge luminescence exists due to the ultraviolet (UV) light from the glow discharge. The rate of the luminescence of the total radiation from the core is at most one‐twentieth the thermal radiation in a steady‐state splicing situation. Further, the apparent core location is expanded by the amount of refractive index due to the lens effect of the clad. Hence, the true location of the core must be calibrated.
Multilevel storage memory using serial—parallel–serial charge—coupled device
Authors: Nakamura Taichi
Published: July 2007

Since the CCD can handle analog signals directly, it is used widely for delay lines, filters, imaging elements and imaging memories. This paper considers the multilevel storage memory of an SPS (serial‐parallel‐serial)‐CCD applied to field memories of image signals. First, a charge transfer model for an SPS‐CCD is created. By means of the transfer function derived from this model, it is clarified that the transfer losses of the serial register and the parallel register degrade the frequency characteristics of the amplitude and phase. It is pointed out that this degradation can be improved significantly by compensation of the transfer losses of the two serial registers and the parallel register. Since realization of a circuit for rigorous compensation of the transfer loss is extremely difficult, a simple transfer loss compensation method is also studied in which the SPS‐CCD is considered as a cascade connection of two serial registers. It is found that the difference in the effect of simple and rigorous compensations is at most 0.6 percent in the case of 50 percent eye degradation. Hence, the effectiveness of the simple compensation is confirmed. Also, by using a commercially available CCD, an experiment for eight‐level storage memory is carried out in which a simple transfer loss compensation is applied. It is confirmed that agreement of the calculated and measured signal error rates is excellent.
CMOS comparator suitable for mixed analog—digital LSIs
Authors: Tsukahara Tsuneo , Ishikawa Masayuki
Published: July 2007

A method of analyzing the effects of clock feedthrough and power supply noise on CMOS comparators is described. In addition, a new flip‐flop type comparator with large tolerance to clock feedthrough and power supply noise is developed.

First, a method of analyzing clock feed‐through and power supply noise tolerance using small signal analysis of the inverter chopper comparator is described. Next, a new flip‐flop comparator whose tolerance to clock feedthrough and power supply noise is significantly greater than that of the inverter chopper comparators is proposed. Experimental results are also described. The new comparators fabricated using 1.5 μm CMOS technology show a small offset voltage (⩽ 1.5 mV) which is caused mainly by clock feedthrough imbalance. The power supply noise tolerance of these new comparators is almost twenty times larger than that of the inverter chopper comparators.
Design considerations for mode—conversion type optical branching waveguides
Authors: Sawa Shinnosuke , Ono Kazuo , Mori Seiji
Published: July 2007

A few comprising methods of mode‐conversion type low‐loss optical branching waveguides are proposed anew, and the fundamental properties are clarified by numerical analysis based on the coupled mode theory. For the analytical model, we select a singlemode slab waveguide, and assume that the waveguide possesses mode transducers at the input and output sides, respectively. The mode transducers are designed in the best possible way for mode conversion from the input to the main part of the branch waveguide and also from that main part to the output waveguide, that is, so as to minimize the radiation loss at the output end of the branching waveguide. The waveguide thus designed has a taper at the input side, and the cross‐sectional shape varies in the direction of the transmission axis. For the analysis, first we calculate the coupling coefficients between the coupled modes of the tapered and branch sections of the three‐layered slab waveguide, respectively. Then we substitute the coefficients into the corresponding coupled mode equation whose solutions are obtained numerically by the Runge‐Kutta‐Gill method. The result of numerical simulations shows that the comprising methods proposed in this paper can reduce the mode conversion loss more remarkably than the other methods known till now.
Geometrical optics field of guided waves. A geometrical interpretation for the field amplitude
Authors: Hashimoto Masahiro
Published: July 2007

Following a previous report [1], this paper describes the geometrical optics theory applied to waveguides. The ray theory to be used as a foundation is based on the Maupertuis principle. It has been pointed out that the theory is not the one based on Hamilton's principle. Both theories are different in concept. However, the difference in the ray trajectory appears only in anisotropic media. In this paper, the anisotropic medium is assumed to be uniform along the waveguide axis whereas it is inhomogeneous in the cross section. Hence, the conventional isotropic waveguides are included in the present theory. The objective of the paper is to construct geometrically the field of the eigenmode propagating in such a waveguide. Since the construction method for the phase of the field has already been reported, the field amplitude is derived mainly from geometrical considerations. Since some examples coincide with the known results obtained from the field theory, it is presumed that the geometrical interpretation of amplitude holds, in general. New geometrical formulas that cannot be derived from the solutions of the wave equation are obtained.
Analysis of two‐core single‐mode optical fibers for subscriber lines
Authors: Yoshikawa Hiroshi , Ohno Yutaka , Kimoto Hisakazu
Published: July 2007

Multicore optical fiber, consisting of several cores in the same clad, has been developed for use as optical fiber cable for subscriber lines, by which high‐density cable can be realized. One of the problems of multicore fiber is crosstalk between adjacent cores. In this paper, a two‐core single‐mode optical fiber, which is the basic structure of the multifiber, is analyzed and an optimum refractive index profile for desired crosstalk and possible high density is discussed. In the analysis, comparison was made between step‐type, W‐type, α‐power and inverse α‐power index profiles, considering the mode field diameter which is an important parameter for a single‐mode optical fiber. The results show that: (1) under the same mode field diameter, the crosstalk for α‐power or for inverse α‐power refractive index profile has little difference with that for the step‐type profile; (2) by the use of the W‐type refractive index profile, high density becomes possible. Based on these results, the design and evaluation of the multifiber can be carried out. To analyze the coupled fiber with a radially inhomogeneous refractive index profile, the point matching method and homogeneous multilayer division method are combined. Although scalar approximation is made in the method, in the case of a weak waveguide, the relative error of coupling coefficients was found to be less than 0.1% even for strong coupling.
Steady‐state analysis of electromagnetic field by vertical electrical dipole over lossy ground
Authors: Ichikawa Satoshi , Karasudani Takashi
Published: July 2007

The lightning discharge effect is shown by a model in which a lightning current climbs to a lightning cloud from the ground. The electromagnetic field induced at the observation point is the integration of the contribution due to an infinitesimal vertical dipole placed on the discharge path integrated along the path from the ground surface to the height of the cloud. When the conductivity of the ground is taken into account, the expression of the electromagnetic field due to the infinitesimal electric dipole contains a term given by a complicated infinite integral called the Sommerfeld integral that includes the Bessel function. For a wave source with an isolated waveform lasting for a short period of time such as the lightning discharge current, the frequency components exist over a broad range. Hence, in the analysis of the transient electromagnetic field by the lightning discharge, the frequency changes significantly with the source location. As a result, the behavior of the integrand in the Sommerfeld integral changes significantly. This paper treats a case in which the wave source varies sinusoidally so that the transient analysis is anticipated and a useful result is obtained for the steady state. To this end, the analysis of the electromagnetic field induced by a vertical electric dipole on the lossy ground is described with special attention given to the numerical processing of the Sommerfeld integral.
Miniaturized optical fiber couplers based on direct–jointing architecture: Loss improvement by a new space–sharing technique
Authors: Sasaki Issei , Yoneta Masaji
Published: July 2007

A miniaturized optical fiber directional coupler based on a new space‐sharing technique has been investigated. To obtain a miniaturized size, we propose a direct‐jointing technique, in which the optical fibers to be coupled are directly jointed without an intermediate of any other optical component. Moreover, an intrinsic excess loss of ‐0.0015 dB in the direct‐jointing architecture is theoretically possible for graded‐index multimode optical fiber systems.

Instead of the conventional power‐sharing technique with a half‐mirror, we use a space‐sharing technique, in which the optical power is divided in space with a distributed digital reflectance (R = 1 or 0) mirror. The present method is advantageous in that it improves the loss characteristics, particularly at a 1:1 division ratio. The excess loss of the conventional half mirror coupler may be more than 2 dB, but the new technique produced a loss lower than 0.5 dB (at λ = 1.55 μm) in a test sample.
Financial analysis: The methods and their application to employee training
Authors: Mosier Nancy R.
Published: July 2007

Training and development is big business; therefore it should be evaluated in the same way as other large investments, in terms of costs and benefits. In this context, training becomes another tool for a firm's survival. According to Nancy Mosier, although training directors recognize the importance of cost considerations, many still use intuitive methods rather than collecting and analyzing hard numbers to justify their programs. Managers can now take heart because Mosier describes some basic and useful techniques to get the cost‐returns analysis rolling. The same applications as are used to justify capital, land, or other resources can be used to justify training and development. Mosier reviews common capital budgeting techniques; for example, payback time, average rate of return, present value or present worth, internal rate of return, and cost‐benefit ratio, and contrasts these techniques with those now being used in training and development. Much of what is available in training focuses on costs and advocates making decisions only on the basis of costs. Her message is clear—financial analysis in training and development must be made on the basis of both costs and returns for the like of the project, and this article helps training directors to look at the complete picture.
The relationship between trainee responses on participant reaction forms and posttest scores
Authors: Dixon Nancy M.
Published: July 2007

In many organizations, the responses to participant reaction forms are the only data managers use when they decide to offer or revise a training course. Is this appropriate? To address this question the author studied the relationship between posttests (tests taken after the course is finished) and the responses on participants' forms for 1,200 trainees in a large manufacturing company. Although the study found no useful correlation between posttest scores and participants' perceptions of (a) the relevance of the course, (b) their own learning, (c) their enjoyment, or (d) the skill of the instructors, it found significant correlations between participants' enjoyment and the ratings of the instructors.
The pretraining environment: A conceptualization of how contextual factors influence participant motivation
Authors: Cohen Debra J.
Published: July 2007

How a training program is introduced may influence a person's motivation to attend and participate actively in the program. A pretraining environment consisting of factors such as the supervisor's style, co‐workers' attitudes toward and experiences with training, the company's publicity about the program, the program's credibility, and corporate attendance policies may have an important effect on an individual's perception of the importance of training and motivation for attending and performing well in the program. An analysis of these contextual factors suggests propositions to predict the influence of the pretraining environment.
A comparison of data collection methods for assessing training needs
Authors: Preskill Hallie
Published: July 2007

This study determined the relative effectiveness of three different data collection methods for conducting needs assessments and concurrently assessed the professional development needs of human resource development employees in a large metropolitan area. A survey using only closed‐ended items, an open‐ended item questionnaire survey, and focus group interviews were used to understand HRD practitioners' training needs, incentives for participating in professional development activities, preferred scheduling options, and reasons that limit professional development. A combined approach using a closed‐ended survey with focus group interviews resulted in a needs assessment method that was both effective and efficient.
Validity in organizational research: A heuristic model
Authors: McKay David A. , Mink Oscar
Published: July 2007

This article outlines the role of the HRD practitioner as organizational research investigator and describes a model for validating measurement instruments, constructs, and strategies in organizational research. The authors review theoretical and conceptual foundations for validating organizational research and present a validation model anchored in communication theory. Common errors and current issues in validation of measurement in HRD research and practice are identified, and uses of the heuristic validation model are illustrated.
A comparison of self‐directed learning readiness in U.S. and Hong Kong samples and the implications for job performance
Authors: Guglielmino Paul J. , Roberts Donald G.
Published: July 2007

A comparative study was made between 753 employees in a U.S. telecommunications company and 655 employees of a Hong Kong telecommunications utility in order to determine whether similarities and differences exist between learning style and job performance. The study revealed a positive relationship between readiness for self‐directed learning as measured by the Self‐Directed Learning Readiness Scale (SDLRS) and job performance in both samples. In general, U.S. respondents scored higher than Hong Kong respondents on the scale.
Using the work group as a laboratory for learning: Increasing leadership and team effectiveness through feedback
Authors: Lawrence Harriet V. , Wiswell Albert K.
Published: July 2007

An experimental field study was conducted in a large municipal government to determine the effects of training designed to improve managers' interactions with their natural work groups. The SYMLOG Leadership Values Instrument was used to measure group and individual effectiveness on three bipolar behavioral characteristics (Dominance‐Submis‐siveness, Friendliness‐Unfriendliness, and Accepting‐Opposing Task Orientation of Established Authority) before and after training. Managers practiced feedback skills and group process methods in the workshop, applied them in the workplace, and received feedback in peer teams at the next session. A statistically significant difference was found, with the treatment group perceiving themselves and their natural teams as more effective and as characterized by greater Dominance and Friendliness. Thus, the increased use of feedback skills caused these managers to view themselves and their subordinate work groups as more proactive, engaged, and cohesive as a team.
Survey of bank sales training practice
Authors: Parker R. Stephen , Pettijohn Charles E. , Carner William
Published: July 2007

This study sought to determine the commitment that banks have made to providing their employees with sales training. The study, which uses a national sample, examines the amount and type of sales training provided and the general attitude held by management toward sales training. Results are given for eight areas: prospecting, approach, need identification, objections, close, postsales service, product knowledge, and self‐motivation. Chi‐square analysis was used to determine whether significant differences existed in the type of training received and asset size. Directions for future research are suggested.
Invited reaction: Level and strategy should and do make a difference!
Authors: Muschewske Robert C.
Published: July 2007

The preceding study did not yield results that supported the authors' hypotheses related to the effects of management level and corporate strategy on management development programs. I contend that this occurred primarily because of a reliance on outdated theories (Katz, 1974), inadequate categories of management development training program content (Burke & Day, 1986), and outdated and/or inappropriate strategy classifications (Hitt & Ireland, 1985) rather than because of a faulty premise—that management level and corporate strategy have an impact on management development programs. My research and consulting experience clearly indicate that they do.