A traveling-wave semiconductor laser amplifier with a thick, short active layer is optimum for achieving insensitive signal gain to polarization while maintaining high-output power and low-noise characteristics.

This paper presents an implementation model for efficient state dependent processing on data flow machines, and some results from evaluation on NTT's data flow machine simulator. In this model, which is based on communicating processes with streams, each element of a stream is sent directly from an instance of a stream-producing function to a corresponding instance of a stream-consuming function. The order of elements in the stream is preserved by schemata for sequentializing instances of the functions. There is no need for data structure on memory for a stream. Therefore, it is expected that the same number of instances of a stream processing function as the number of elements in the stream are invoked and executed nearly in parallel. A nondeterministic processing is realized in the same framework. Evaluation results show that this model can attain about 80% improvement in speedup compared with a conventional model which exploits parallelism by a non-strict data structure constructor, eager evaluation of element data, and a memory with synchronization capability. It is also shown that a mutually exclusive processing in a sample program, i.e. a functional level simulator of a data flow machine as implemented by this model, does not constrict parallelism.

To employ Computer Graphics (CG) technology in the production of CG holograms or similar applications where the generation of consecutive pictures with rotated viewing directions is demanded takes a lot of time and money. This paper presents a two-pass surface rendering method for fast creating such animated pictures from a single view image structure. Instead of generating display data for a single picture, the first pass program constructs a Position Oriented (PO) frame buffer that contains the information of control points on every order of visible surfaces. A display program of second pass manipulates the frame buffer structure to generate surface rendered pictures with spatial and perspective transforms. Experiments proved the method is effective to create high quality surface rendered images with rotation capability. Various usuful facilities for CAD visualization have also been developed within the technique. The improvements on memory consumption and picture quality are also discussed in this paper.

GaAs MESFET characteristics in the temperature range of 300 K to 500 K have been investigated using a two-dimensional device simulator. The temperature dependence of the threshold voltage, K-value, subthreshold current, source-to-gate capacitance, and cutoff frequency is theoretically explained.

A direct procedure to realize pipelinable low-sensitivity digital filters is developed only in the z-domain. It is possible to realize arbitrary digital transfer functions using this procedure. The key concept for the low-sensitivity property lies both in the matching concept in doubly-terminated lossless networks and in the localization of transmission zeros. The synthesis procedure is based on successive extractions of transmission zeros by means of lossless but not always reciprocal transfer scattering matrices. Since a transfer scattering matrix involves the transmission zeros as its poles, such a matrix is suitable for their localization. Furthermore a universal first/second-degree section is derived explicitly.

A method of designing digital FIR transmitter and receiver filter pairs for classes and partial response systems is presented. The truncated ideal impulse response of a specified class is used as an initial response of the filter pair in cascade. For class I filter, the impulse response has an even symmetry, then its transfer function is a linear phase lowpass function of case 1 or case 2. Therefore, the passband zeros occur in mirror image quadruplet (and doublet) and the stopband zeros occur on the unit circle. The initial stopband attenuation slopes gradually up as frequency increases. To get an equiripple stopband attenuation for both filters, the passband zeros inside and outside the unit circle are assigned to transmitter and receiver filters respectively, then the stopband zeros of each filter are redetermined. Both filters form a matched filter pair. Next, the passband zeros of the filter pair are adjusted to give minimum intersymbol interference (ISI) in the overall response. For class filter, the impulse response has an odd symmetry and its transfer function is a linear phase lowpass function of case 3. In this case, the filter pair are designed to have equiripple and nearly the same stopband attenuation. Zero ISI approximation is performed similarly. Two design examples are shown. One is a 57th order class I filter pair having 0.05% ISI. The other is 61st order transmitter and 57th order receiver class filter pair whose ISI is 0.2%.

A nobel Hilbert transformer is realized by adapting instantenuous spectrum analysis, namely short time discrete Fourier transform (ab. in ST-DFT). The ST-DFT Hilbert transformer is substantiated to be almost ideal in both phase shifting and amplitude characteristics via experiments for unit sample response and analyzing its power spectrum.

The effect of frame truncation error is discussed with emphasis on difference between existing DFT and new short time DFT. Existing DFTs suffer from fluctuations on spectrum analysis results caused by limitations to their input signals. In this paper, short time DFT is discussed to be free from frame truncation error and to introduce various profit into new spectrum analyzers.

Y-Ba-Cu-O films sputter-deposited at about 650 in high oxygen concentration gas are superconductive without heat treatment after the deposition. The films of 700 nm thickness have Tc end of 72 K on SrTiO3 and 65 K on sapphire substrates. Reduced interdiffusion, compared with post-annealed films at high temperatures, between the film and the substrate is confirmed.

An experimental relationship between byte-organizations and byte-error characteristics for optical disks is discussed. A two-dimensional byte-organization is proposed to decrease byte-errors, based on measured results. This byte-organization is effective in parallel-track recording.

A simple approximation method to calculate scattering from a grid with straight strips of finite size (the equivalent grid method) was proposed by the authors. This method can deal with arbitrarily polarized incidence with arbitrary plane of incidence. In this letter, the applicability of this analysis to the scattering from a grid with curved strips is demonstrated by experiments.

Using an improved calculation method, the transmission coefficient of a quadruple barrier resonant tunneling diode is calculated. Using this result, extreme values of the transmission coefficient and the full widths at half maximum (FWHM) of the resonant peaks are calculated. It is shown that the first terms of the expressions |θ|, which are proportional to the FWHM, are given by the same formula in double, triple, and quadruple barrier diodes.

A plastics such as polycarbonate take a graded birefringent orientation when a high dc ununiform electric field is applied to its molten phase. This ununiformity is maintained even in a solid phase after decreasing the temperature. Therefore, the plastic plate operating as a variable retardation plate is easily and inexpensively fabricated by using this bulk plastics with graded birefringence.

In this paper, we introduce the concepts of multi-node and mono-node to expand the expansive graph grammar given by Shi and Fu to a larger family, the family that contains all rooted acyclic directed graphs. Shi and Fu's approach deals with rooted acyclic digraphs containing only mono-nodes. The ways of numbering and representing rooted acyclic directed graphs are modified and grammars for such graphs are given so that directed graphs containing even multi-nodes can be treated. Parsing algorithms are also given which are described with State-Space representation. Our algorithms are as efficient as those of Ref.(6). We have removed a constraint that the basis graph must be a tree from the expansive graph grammars of Ref.(6) without increasing the space or time complexity of numbering, rewriting and parsing.

Optical characteristics of the Bragg filter fabricated with a Ta2O5/SiO2 optical waveguide are studied. The Bragg reflector was formed by the holographic method using an He-Cd laser. Filter responses were measured with the color-center laser and the stopband bandwidth was found to be 3.5 Å.

Switched-Capacitor (SC) low-pass ladder filters based on the LDI transformation, have been successfully designed using the Lossless Discrete Integrators (LDIs) as their basic building blocks. However, the design of highpass ladder filters with the LDIs are not straightforward as the low-pass or bandpass case. On the other hand, a high-pass design is achieved easily by using a differentiator as the building block, instead of an integrator. Thus, a new design technique of Switched-Capacitor Modified Lossless Discrete Differentiators (MLDDs) is proposed in this paper. By using them as the basic building block, SC high-pass ladder filters are directly constructed based on the low-pass to high-pass transformation. Furthermore, a fully-differential architecture is applied to this MLDD design, and some MLDD alternatives are investigated for high-frequency and time-sharing applications.

In order to effectively solve a three-dimensional unsteady convective diffusion equation, kernel approximation is introduced into the boundary integral procedure in the boundary-element method. It is shown that the present method gives a good approximate solution of the convective diffusion equation in case of not a dominant convection. Also, we find that very fast numerical integration can be carried out on supercomputers.

With the development of LSI technologies, conventional circuit simulation using only single type of method has become unsatisfactory, i.e. circuit-level analysis based on device model spends much simulation time and relaxation methods have the problems on their accuracy. Therefore, it is necessary to develop the better methods to realize both high-speed and good accuracy. In this paper, a mixed-mode circuit-timing simulation method has been studied. It uses a new kind of automatic circuit partition approach--dynamic circuit partition process based on checking coupling factors between circuit nodes at every time point for better convergence. This method is based on examining the characteristic of circuit equations rather than circuit topology or function blocks. A mixed-mode simulation program--MMAPC for transient analysis of CMOS large-scale circuit has been developed and some simulation examples have been performed. The results show that MMAPC can be more than two orders of magnitude faster than a standard" circuit-level simulator (SPICE-like) while providing comparable waveform accuracy, and has better convergence property than general timing-level simulators.

A new type of a dynamic-single-mode laser, which has distributed reflector (DR) both in active and passive regions, is proposed and analyzed to attain high output efficiency with the superior single mode property without increase of threshold current density.

Reliability of single-loop networks can be improved using double loops: forward loops advancing to the neighboring node and backward loops skipping by a certain distance. In this type of double loop networks, when some nodes break down, there exist possibilities that a message can not be transmitted to some nodes and many messages concentrate on some specific nodes to take a roundabout route. Then, the delay may happen in date transmission. These phenomena depend on the situation of faulty nodes. This paper, first, presents a routing algorithm to find a route where a message can be transmitted to the destination node when a multi-node failure arises. Next, the upper bound of transmission steps required to transmit n packets in parallel from respective starting nodes to respective destination nodes is investigated.