bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miniaturization of 35‐GHz NRD‐guide transmitter and receiver
Authors: Uchida Izumi , Kuroki Futoshi , Yoneyama Tsukasa 
Published: July 2007

AbstractThe performance of the 35‐GHz nonradiative dielectric waveguide (NRD‐guide) transmitter and receiver has been improved and they have been reduced in size. the miniaturization of the transmitter has been proposed by reducing the size of the terminator. Since the reflection of the balanced mixer for heterodyne detection has been reduced, miniaturization of the receiver is obtained by removing the circulator used for protection from reflection. the new transmitter and receiver are reduced to half their earlier sizes. Their frequency stability is less than −0.6 ppm/°C. Moreover, horn antennas with rigidity and air tightness are connected to the transmitter and receiver.
Development and application of optical shutter made of PLZT ceramics
Authors: Seino Taisaku , Watanabe Michihiro 
Published: July 2007

AbstractUsing PLZT, which is a transparent ceramic with an electrooptical property, an electrooptical device for high‐speed modulation was fabricated. PLZT was synthesized by the oxide mixing method and the oxalate method in ethanol solution.Using ethanol as a dispersion medium in the former method, the grain size which strongly influences the transmittance can be controlled. the structure of the optical shutter made of PLZT was determined by investigating the electric field distribution in the unit device forming the shutter by the finite element method. Then the optical shutter was formed by patterning the PLZT wafer using photolithography.A three‐dimensional (3‐D) image display system by stereoscope was constructed. the PLZT device was capable of switching display image at 60 and 120 Hz. This device was also usable for 3‐D image display.
Optmum design of low‐voltage and high‐efficiency GaAs power module
Authors: Maeda Masahiro , Ota Yorito , Ishikawa Osamu 
Published: July 2007

AbstractA highly compact GaAs power module designed for the portable analog telephone system has been developed [1]. the module is a two‐stage GaAs power amplifier operable at 4.7 V and is capable of delivering an output power of 32.2 dBm with a power‐added efficiency of 65 percent and harmonic levels less than −40 dBc at 900 MHz.Parameter extraction from two GaAs MESFETs (first‐ and second‐stage FETs) operable at 4.7 V, module design employing a front stage FET whose output characteristics are optimized at a load of 50 ω, and the optimization of harmonic control circuit suppressing the harmonics and improving the drain efficiency are performed by simulation and the obtained results are confirmed by experiments.
Saw filters for high‐power use in cellular radio portable phones
Authors: Hikita Mitsutaka , Shibagaki Nobuhiko , Akagi Takatoshi , Sakiyama Kazuyuki 
Published: July 2007

AbstractBefore a SAW filter is applied to the high‐power section of a cellular radio portable phone, it is necessary to develop a higher‐performance filter with a high‐power capability and a small, nonlinear effect. In this paper, as a new type of filter, a SAW resonator coupled filter of an extended type is proposed which uses two types of piezoelectric substrates. A design method considering the impedance matching between the substrates is presented as well as the results of the experimental duplexer satisfying the specifications of the cellular radio portable phone for the United States. This filter has a third‐order nonlinearity effect that results in the spurious response sensitivity much smaller than the conventional transversal type. These characteristics are almost identical to those for the present dielectric resonator duplexer for the forementioned use.
Basic properties of anodized porous silicon formed under uniform current density
Authors: Aoyagi Hidekazu , Motohashi Akira , Kinoshita Akira , Aono Tomoyoshi , Satoh Akinobu 
Published: July 2007

AbstractPorous silicon is formed by anodization of single crystalline silicon under various current densities and HF concentrations which are the important parameters for anodization. Anodization is carried out in HF solution at constant temperature under a constant current density distribution.This paper describes the fabrication process dependencies of dissolution valence, porosity, and layer formation efficiency which are related directly to the anodization conditions. In addition, the mechanical strength of porous silicon obtained by the hardness measurement was related to the self‐standing limit of porous silicon obtained by a cylindrical model for pores arranged in the twodimensional lattice.
Analysis of thermoelectric power generation using thermoelectric element
Authors: Ogawa Yoshihiko , Watanabe Hideo , Sakai Motohiro , Tunou Katsuhiro 
Published: July 2007

AbstractRecently, there has been renewed interest in the thermoelectric power generation based on the thermoelectric element with a view to the recycling of wasted heat. the existing theory on this subject, however, has been derived from a macroscopic viewpoint such as thermal balance. Since no differential equation is solved, it was not possible to analyze even fundamental subjects such as derivation of the temperature profile inside the element.In this paper, by means of a newly derived nonlinear thermoeleetric differential equation, the temperature profiles and generated output power are analyzed accurately with actual material data. From the analysis, various conclusions are derived. Further, the analysis results by a differential equation which is a linear approximation of the original nonlinear equation are compared with those of the nonlinear equation. It is shown that good agreement is obtained. Also, the previous theory is compared with the analysis results of the linear differential equation. It is pointed out that the previous theory has a certain degree of validity.
Characteristics of a Čerenkov laser improved by loading a kerr‐like medium
Authors: Shiozawa Toshiyuki , Utsunomiya Eiji , Ueda Tetsuya 
Published: July 2007

AbstractIn the čerenkov laser, as the electromagnetic wave grows by gaining energy from the electron beam, it loses kinetic energy and, thus, its drift velocity decreases. As a result, the synchronism between the propagation velocity of the electromagnetic wave and the drift velocity of the electron beam ceases to be kept and efficient growth of the electromagnetic wave is prevented. to overcome this difficulty, this paper proposes a model for the čerenkov laser loaded with a Kerr‐like medium, the permittivity of which increases in proportion to the square of electric field. Also, a numerical investigation is made to determine how the growth characteristics for the electromagnetic wave are improved with the aid of the finite element method.The numerical result shows that, by choosing a proper value for the nonlinear coefficient of the Kerr‐like medium, the propagation velocity of the electromagnetic wave can be delayed in accordance with the decrease in the drift of the electron beam. Thus, the growth characteristics for the electromagnetic wave can be improved greatly. In addition, it is found that the interaction distance to maximize the electromagnetic wave power extracted from the electron beam can be shortened compared with the case where only a linear dielectric is loaded.
Temperature dependence of led intensity due to filter effect of Sinx
Authors: Toyama Toshihiko , Tanaka Yukio 
Published: July 2007

AbstractThe filter effect of an SiNx film used to passivate a light‐emitting diode (LED) was investigated. the transmission spectrum of an SiNx film is dependent on the film thickness, while the wavelength of light emitted from an LED depends on temperature. Therefore, the intensity of emitted light depends on the temperature characteristic of the thickness of the SiNx film. LEDs with SiNx films whose thicknesses were (3/4 + 15%) λ were realized.The simulation indicated that the content of the temperature coefficients of emission intensity due to the filter effect was between −0.049%/°C and +0.072%/°C when the thickness of the SiNx was varied as described in the foregoing. On the other hand, the experimental results on the variation of the temperature coefficient due to the filter effect was between −0.01 %/°C and +0.03%/°C. In this study, the agreement between the simulated and experimental results were not in quantitative agreement because the temperature coefficients of the LEDs were not uniform in comparison with the component due to the filter effect.
Analysis of marks recorded on magneto‐optical media by the magnetic field modulation method
Authors: Shibuya Giichi , Matsumoto Mitsunori , Morisako Akimitsu , Shibahara Masanori 
Published: July 2007

AbstractThe readout signal waveform and recorded mark of magneto‐optic write media are investigated using the magnetic field modulation method. Because overwrite is possible in the magnetic field modulation method, it has been applied to a small magneto‐optic disk in a new audio media system. the magneto‐optic mark recorded by this system has a chevron shape, and the width is highly sensitive to changes in such factors as laser power or ambient temperature. For this reason, it is necessary to design the recording medium so that a sufficiently stable readout signal is obtained for these changes.A numerical integral obtained by polygonal approximation of recorded mark is used, and the readout signal waveform is determined by simulation. By this technique, the readout signal amplitude and crosstalk level that influence the medium and the recording density are determined. Based on this result, the write density of the medium is computed and comparison with measurement values indicates that agreement is excellent. Moreover, by adjusting the tracking offset during readout, it is possible to improve the apparent write power margin. Thus, the technique will be very effective in the design of future high‐density recording media.
Fractal analysis on pore structure for activated carbon fibers
Authors: Endo Morinobu , Takeuchi Kenji , Sasuda Yoshihiro , Matsubayashi Ken'Ichi , Oshida Kyoichi , Dresselhaus Mildred S. 
Published: July 2007

AbstractRecently, the active carbon filter (ACF) has drawn attention because of its usefulness in the electrical and electronics fields. to improve the quality of ACF, the microscopic structure of this material must be analyzed. One method is to observe the structure using a transmission electron microscope (TEM).Recently, the capability of the TEM has been improved drastically. Not only can its molecular structure be observed but also numerous analytical equipment has been attached to it. ACF has been investigated by using a TEM, and it has been found that the ACF structure was so complex that quantitative analysis was impossible.Computer analysis of a TEM image has also been attempted. In this analysis, the TEM image was processed by the two‐dimensional fast Fourier transform and fiequency analysis to investigate the distribution of the pore diameter of ACF. As a result, it was speculated that the pore shape was fractal. Then, it was shown that the contour of the pore cross section was fractal and the fractal dimension was obtained. When the structure was too complex to analyze only by TEM analysis, the introduction of the image processing method was effective.
A branch‐line eight‐port hybrid circuit
Authors: Kawai Tadashi , Lio Ken'Ichi , Ohta Isao 
Published: July 2007

AbstractThis paper deals with a circuit in which a total of eight ports made of two sets of four ports are mutually separated and in which the input from one port is delivered to four ports of another set with equal amplitudes with a certain phase relationship. This circuit is called the eight‐port hybrid circuit and is an extension of the characteristics of a conventional (four‐port) 3‐dB hybrid to the case of eight ports. A circuit configuration is proposed by means of four branch‐line‐type 3‐dB hybrids.First, by taking advantage of the symmetry of the circuit, an analysis is carried out. the relationship to be satisfied by the characteristic admittances of each branch line is determined. the frequency characteristics of the scattering matrix elements are presented.Next, a design method for broadening the bandwidth is given for the matching circuits to be attached to each port and quarter wavelength transmission lines connecting each hybrid. A relative bandwidth of about 20 percent is realized. Also, the test circuit is measured and the validity of the design method is confirmed. the present circuit is advantageous in that the circuit configuration is possible on one side of the substrate by means of strip lines and all eight ports are directed outward so that connection with other circuits is simplified.
Fabrication ofpin/hemt receiver oeics for Gb/s lightwave systems on three‐inch diameter inp substrate
Authors: Yano Hiroshi , Doguchi Kentaro , Murata Michio , Nishiyama Naoki , Sasaki Goro , Hayashi Hideki 
Published: July 2007

AbstractReceiver optoelectronic integrated circuits (OEICs) have been successfully designed on a three‐inch diameter InP substrate. Epitaxial layers grown by OMVPE on three‐inch diameter InP substrates showed good uniformity of electrical and optical properties. By using the epitaxial layers, transimpedance‐type receiver OEICs were fabricated. the receiver OEICs over a three‐inch diameter InP substrate showed an average bandwidth of 2.78 GHz with a standard deviation of 280 MHz. the receiver also exhibited a transimpedance of 61.1 dB and a sensitivity of ‐24.9 dBm for 2.4 Gb/s input signals. These results indicate that the receiver OEICs designed on a three‐inch diameter InP substrate are ready for practical use in Gb/s lightwave systems.
Integrated coupling device between a laser diode and an optical fiber using a microlens
Authors: Shimada Jun‐Ichi , Ohguchi Osamu , Sawada Renshi , Tanaka Hidenao , Watabe Akinori 
Published: July 2007

AbstractAn integrated coupling device between a GaAs/Al‐GaAs laser diode and an optical fiber using a microlens is described. It is calculated that the high single‐mode fiber coupling efficiency of 81 percent is obtained for the microlens with RMSA of 0.4 λ and that the large alignment tolerance of 55 μm is obtained in thez‐direction. It is demonstrated experimentally for single‐mode fiber coupling that the coupling efficiency is 26 percent and that the alignment tolerance in thez‐direction is 19 μm. the differences in the coupling efficiency and alignment tolerance between the calculation and experiment are due to a mismatch of beamwidth and the fabrication error of the fiber guide. Additionally, measurement of the oscillation spectrum of this coupling device, which has a composite cavity, showed that an LD with a microlens and fiber causes multimode oscillation due to reflection from the fiber facet.
Integrated optic grating scale‐displacement sensor using linearly focusing grating couplers
Authors: Ura Shogo , Shinohara Masayuki , Endoh Toshiaki , Hiroshi Nishihara Toshiaki Suhara 
Published: July 2007

AbstractAn integrated optic sensor was proposed and demonstrated for measuring displacement of a grating scale. the sensor is constructed by integrating a pair of linearly focusing grating couplers (LFGCs) and a pair of photodiodes (PDs) in a glass waveguide on an Si substrate. Two beams, radiated from the LFGC pair, overlap on the grating scale with each other. the beams diffracted by the grating scale interfere on the PDs, and the interference signals vary when the grating scale moves along its grating vector direction. the device was designed and fabricated, and the variation of output photocurrents was confirmed experimentally.
Realizing a completed‐resonant level by using an asymmetrical triple‐barrier structure
Authors: Ren Jie , Nagai Nobuo , Ohtani Naoki , Miki Nobuhiro 
Published: July 2007

AbstractBecause of the rapid development of quantum effect devices, it is necessary to obtain a synthesis method which can give the expected quantum effect symptoms. Using a triple‐barrier structure, quantum effects which cannot be obtained with a double‐bather structure can be realized. However, only a few studies have been made on the triple‐bather structure, in particular, on the asymmetric triple‐bather structure.In this paper, based on the circuit theoiy, the syn thesis method of an asymmetrical triple‐barrier structure where a single perfect resonant level is formed in its quantum well is proposed. It is assumed that an original symmetrical double‐barrier structure has a first resonant level E1 and a second resonant level E2 whose resonant energy is four times higher than that of E1. One of the single barriers is replaced by another symmetrical double barrier with the first resonant level equal to the second resonant level E2 of the original one.In the nonsymmetrical triple‐barrier structure formed by the forementioned method, the transmission probability at E1 is 1 and that at higher‐energy levels is sufficiently low. This synthesis can be achieved by using the power reflection coefficient and the Smith chart of a complex equivalent circuit. the validity of this method can be established by means of the Smith chart. By carrying out a numerical calculation on the electron transmission characteristic of the synthesized nensymmetrical triple barrier, it was confirmed that the transmission probability at the energy level that is four times higher than E1 can be around 0.1.
Design and operation of josephson circuits using ruffle gates with a stacked structure
Authors: Nagaishi Hideyuki , Nakahara Kouji , Hasegawa Haruhiro , Nishino Tosikazu 
Published: July 2007

AbstractDC‐powered Josephson logic gates have the advan tage of being free from operation error due to crosstalk from power current in contrast to ordinary ac‐powered Josephson logic gates. One of these, the HUFFLE (hybrid unlatching flip‐flop logic element) gate using stacked Josephson interferometers (JI) can execute complicated logic functions by itself. Therefore, high‐Speed operation of logic circuits using HUFFLE gates may be expected because the number of logic stages in the circuits is reduced. to investigate the improvement in circuit per formance by using HUFFLE gates with the stacked structure, the authors have fabricated a 6‐bit arithmetic logic unit (ALU) and tested its operation. Two new logic gales, exclusive OR and majority, newly developed using the stacked structure have been developed. the ALU which performs the four functions, AND, OR, exclusive OR, and ADD, is realized with seven logic stages. Ac cordingly, reduction in the number of logic stages and execution time of the ALU by use of the stacked HUF FLE gate family is confirmed.
LiNbO3 optical waveguide devices
Authors: Minakata Makoto 
Published: July 2007

AbstractThis paper describes the present status of LiNbO3 optical waveguides with respect to the optical grade crystal, growth process, dc drift, and optical damage. In addition, the wideband optical modulators, QPM‐SHG blue light source and epitaxial growth of LiNbO3 are reported. Optical grade crystals are needed for devices described in the foregoing and the requirements for such crystals have been proposed.The physics of optical waveguides has been understood and the relationship between the device properties and fabrication processes has been clarified. Methods to suppress the dc drift which has been one of the obstacles in practical applications of optical waveguides have been established. the solutions to minimize the optical damage in SHG devices have been found.Recently, drift‐free optical modulators and wideband optical modulators for 70‐GHz applications have been reported. Because of the rapid progress in polarization inversion technologies, SHG devices for blue‐light emission with an output power of 20 mW and a conversion efficiency of 600 percent/Wcm2 have been developed. Solid‐state lasers formed by doping Er and Nd to crystals have been investigated. the research of growing an LiNbO3 thin film to form an optoelectrical integrated circuit has been carried out.
A solution method based on the coupled‐mode theory for natural single‐phase unidirectional surface acoustic wave transducers
Authors: Hasegawa Koji , Inagawa Kiyoshi , Koshiba Masanori 
Published: July 2007

AbstractA method for analysis of natural single‐phase unidirectional transducer (NSPUDT), which is one of unidirectional surface acoustic wave interdigital electrodes, is proposed in which the mode coupling theory and the finite‐element method are used. the finite‐element method is used for calculations of the upper and lower limit frequencies of the stop band, the potential standing wave distribution at these frequencies, and the static capacitance per electrode pair for the short and open gratings corresponding to the electric terminals either shorted or open. In the substrate used for NSPUDT, the locations of the maximum and minimum of the standing wave in general vary in the depth direction of the substrate. Hence, it is not possible to use the standing wave pattern in the substrate as is used for a substrate surface where electrodes are present. the variation of the potential in the depth directional of the substrate is incorporated into the mode coupling theory in this research, so that the depth dependence of the standing wave profile is qualitatively evaluated. Hence, it is made possible to confirm the locations of the maximum and minimum of the standing wave at the substrate surface from the standing wave profile in the substrate.Specifically, the present method is applied to NSPUDT on an ST‐cut 25deg; X‐propagation quartz substrate so that its validity and usefulness are confirmed.
Photonic networks
Authors: Miki Tetsuya 
Published: July 2007

AbstractOptical communication systems underwent rapid development during the 1980s, and 10‐Gb/s systems are now being developed. Furthermore, asynchronous transfer mode (ATM) technology is being applied to the development of transport nodes with throughputs of 20 to 100 Gb/s for communications networks. However, such speeds are close to the limits of what can be achieved with systems based on electronic processing and, in the near future, it will become necessary to change over to photonic networks in which processing is done optically. Photonic networks are not just characterized by high speed and wide bandwidth; it is also possible to build them with a simple yet flexible configuration. This paper gives an overview of how photonic technology can be introduced in different parts of a network, including the core network, the access network, and private networks, and describes the areas requiring further research. Research into fundamental devices is also progressing, and research into photonic networks is also being actively pursued in the West. Photonic networks will form the foundation of wideband networks in the next century, and their research is extremely important.
Calculation of Q factor and treatment of curved conducting wall in cavity analysis by FD‐TD method
Authors: Lida Yukio , Morita Masanobu 
Published: July 2007

AbstractIn this paper, a method for computing a Q value is proposed, which is believed useful for a high Q cavity. In this method, the Q value is derived from the input excitation energy and the stored energy in the process of increasing amplitude of the electromagnetic field in the cavity. This method is applied to a rectangular cavity without an aperture and the Q value obtained has an error of only approximately 1 percent.In this paper, a cylindrical cavity without an aperture is used as an example and the surface processing is investigated by means of the electromagnetic field distribution in the cavity and the wall loss. In the stair‐stepped approximation of the cylindrical wall surface, the electromagnetic field is disturbed significantly near the wall in the case of the TM010 and TM011 modes which have magnetic fields in the azimuthal direction. In addition, the Q value is higher by 21 × 32 percent and the computed wall loss is too small. Using CP method analysis, in which the integration path is modified to fit the boundary for wall processing, both the electromagnetic field and the wall loss are computed accurately.