Asynchronous Transfer Mode (ATM) switching system is expected to handle various kinds of media (such as motion video, computer data, and voice), and traffic control becomes essential to satisfy various quality requirements and to maintain efficient utilization of system resources. Priority control is one possible solution for realizing such a traffic control. In priority control, cells from various media are scheduled for transmission with different priority according to the quality class to which they belong. In this paper, we propose a new priority control method in which cells from various media are stored in their own buffer, we call it class buffer, and priority assignments are carried out based on the number of cells in each class buffer and the delay time. The number of cells in each class buffer is maintained using the counter circuit. The delay time of the cell is checked by the timer circuit for cell group, each of which consists of cells arriving during a periodical time interval. For simulation model, we consider three kinds of traffic; video, computer data, and voice, of which quality requirements are quite different. We show performance results in terms of the cell delay and the cell loss probability in our method through simulation.

In this letter, it is clarified that the quantum noise properties of the linear amplification and locking amplification in the injection locked laser process are different. The noise property of the locking amplification is newly given.

In this paper, we analyze a photodetection process of new kind theoretically, which transforms a coherent state of light so as to lead to nonstandard property, namely, sub-Poissonian distribution of its output photoelectron during its photodetection process. The properties of the photoelectron distribution are studied used as preamplifiers of both direct-detection and homodyne detection cases.

After the intrinsic pulsed light illumination, a transient negative photoconductivity (TRANP) was observed in silicon doped with gold. The ambient temperature dependence of the TRANP-current was measured and compared with the simulated results obtained by solving rate equations. The temperature dependence of the peak value of the TRANP-current was in agreement with the simulated result. The activation energy of gold acceptor level obtained from the time constant in the recovery process was also consistent with the simulation. It was cleared from this result that the recovery process is dominated by the electron re-emission from gold acceptor level to the conduction band. It was concluded that the occurrence of the TRANP is well explained by using our model proposed before.

This letter considers a subclass of t-symmetric error correcting/all unidirectional error detecting (t-SyEC/AUED) codes in which the information is represented in an m-out-of-k coded form, which thus can be regarded as virtually systematic for practical purposes. For t3, previous researchers proposed methods for constructing codes of this subclass which are either optimal or of asymptotically optimal order. This letter proposes a new method for constructing, for any values of t, m and k, codes that are either optimal or of asymptotically optimal order. The redundancy of the obtained code is of the order tlog2k bits when mt.

The a-Si films deposited on quartz substrates were crystallized by lateral sweep annealing in steep temperature gradient using a gas burner. Random nucleation in amorphous region was effectively suppressed in the temperature gradient, so lateral solid phase epitaxial growth from crystallites generated at the initial stage of lateral sweep annealing spread over 100 µm. Their crystallographic orientations were mostly (100).

We will introduce W-trees of a W-graph which is a graph containing wild components. A wild component is an incompletely defined subgraph which is known to be a tree but what kind of the tree is unspecified. W-tree is defined as a set of edges and vertices of wild components obtained from a non-sigular major submatrix of a W-incidence matrix. The properties of a W-tree are useful for studying linear independent W-cutsets and so on in a W-graph.

In case of the system identification problem, such as an echo canceller, estimated impulse response obtained by the frequency-domain adaptive filter based on the circular convolution has estimation error because the unknown system is based on the linear convolution in the time domain. In this correspondence, we consider a sufficient condition to reduce the estimation error.

Surface damage to n-type silicon wafers induced by Reactive Ion Etching (RIE) with CF4 gas was evaluated using X-ray photoelectron spectroscopy (XPS) and the current-voltage (I-V) characteristics of Au/n-Si Schottky diodes fabricated on the damaged surface. The reaction products (SiF, SiF2, and SiF3) in the damaged layer were detected by XPS. Assuming the surface damage on a silicon wafer induced by RIE acts as a donor, the donor density was found to be about 21019 cm-3. The distribution of SiF3 and the donor density in the depth direction were almost equal. The thickness of the damaged layer was about 15 nm. These findings suggest that the donor in the damaged layer on a silicon surface induced by RIE may be SiF3.

A laser/microwave method using two lasers of different wavelengths for carrier excitation is proposed to evaluate Si surfaces. These constitute a He-Ne laser (wavelength=633 nm, penetration depth=3 µm) and a YAG laser (wavelength=1060 nm, penetration depth=500 µm). Using a microwave probe, the amount of excited carriers can be detected. The carrier concentration is mainly dependent on the condition of the surface when carriers are excited by the He-Ne laser, as well as on the condition of the bulk region when carriers are excited by the YAG laser. Microwave intensities detected under the He-Ne and the YAG lasers illumination are referred to as the surface-recombination-velocity-related microwave intensity (SRMI) and the bulk-related microwave intensity (BRMI), respectively. The difference between SRMI and BRMI is called relateve SRMI (R-SRMI), and is closely related to the condition of the surface and surface active region. We evaluate the surfaces of the samples after plasma and wet etching to remove the photoresist layer. And we evaluate the surfaces of the samples after heat or HF treatment which is done to recover the damage introduced by plasma etching. It was found that the R-SRMI method is better suited to surface evaluation than conventional lifetime measurements.

Silicon-on-insulator (SOI) films fabricated by the wafer bonding technique were studies with capacitance-voltage (C-V) and deep-level transient spectroscopy (DLTS) measurements. For our expereiments, two kinds of SOI wafers were prepared. Many voids were present in one sample (void sample), but few voids were in the other sample (no void sample). Before annealing, two DLTS peaks (Ec-0.48 eV and Ec-0.38 eV) were observed in the SOI layer of the void sample. For the no void sample, different two DLTS peaks (Ec-0.16 eV and Ec-0.12 eV) were observed. The trap with an activation energy of 0.48 eV was annealed out after 450 annealing for 24 h. On the other hand, other traps were annealed out after 450 annealing for several hours. During annealing at 450, thermal donors (TDs) were formed simultaneously. In usual CZ silicon, a DLTS peak of TD was observed around 60 K. In the no void sample, however, a TD peak was observed at a temperature lower than 30 K. This TD was annihilated by rapid thermal annealing. This suggests that the TD with a shallower level was formed in the no void sample after annealing at 450.

Isotope dilution secondary ion mass spectroscopy (ID-SIMS) using 30Si as a spike is investigated as a quantitative analysis method for trace amounts of Si. For a standard solution of Si, the relateve standard deviation of results using this method is 5% for 0.2 µg Si, and the determination lower limit is 18 ng. Using this method, the amount of Si deposited on the Ge(100) surface by the self-limited adsorption of SiH2Cl2 is determined to be about 1.00.2 monolayer.

Recently most of the singularities of the equivalent edge currents for flat plates were eliminated by the authors using the paths of most rapid phase variation. A unique direction on the plate was determined for given incidence and observer. This paper extends this method for arbitrary angle wedges and presents the new expressions of the equivalent edge currents. The resultant expressions are valid for any incidence and observation aspects and have no false singularities. Diffraction patterns and radar cross sections of 3-D objects composed of wedges are calculated by using these currents. They show good agreements with experimental data or the results by the other methods.

In this paper, we propose a method to simulate the curve surface of the initial height in the movement of the electronic wire bonder using the experimental data. For given measured data (xk, yk, zk (k=1, 2, , m)), we propose an algebraic surface of n-th degree as a methematical model of the initial height surface. The AIC method is a method of evaluating the goodness of a given model. The maximum likelihood model is selected by comparing with the AIC value of each model for n=0, 1, 2, 3, , 11. Useing this model, the initial raise position of the electronic wire bonder can be controlled by computer programing and can make the movement of wire bonder full-automatic. As a resurt, the well-arranged wiring and reliable contacting can be obtained.

Analysis of the propagation of circularly symmetric fields is made using the finite-difference beam-propagation method. After testing the accuracy of this method, we analyze the guided-mode transmission of connected fibers whose core radii are different. The propagation behavior of the unguided-mode field generated at the junction is revealed using a transparent boundary condition.

A passive double star (PDS) optical subscriber system which employs a newly proposed flexible access and frequency division duplex transmission system has been reported. For the flexible access and efficient channel usage in subscriber PDS system, a modified pipe-line polling with a call-by-call basis channel assignment has been proposed. This access system has a wide covering range which exceeds 10km or more. A newly proposed pulsed PSK transmission and a baseband transmission are used for a single wavelength bi-directional transmission for to and from the central office. A pulsed FM single subcarrier transmission system is also proposed for the analog CATV distribution system, which is overlaid with wavelength division multiplexing on the bi-directional transmission system. The equipments for the pulsed PSK and the pulsed FM transmission can be realized with all digital circuits. Moreover, the pulsed signal's modulation nature has eased the requirement for the laser diode characteristics, such as linearity and RIN. These features are effective for the compact and cost effective transmission systems.

A new channel stop design for submicton local oxidation of silicon (LOCOS) isolation was presented. The n-channel stop was designed with boron implanation after forming LOCOS, while the p-channel stop was constructed with high energy phosphorus or arsenic implantation before or after forming LOCOS. These optimized channel stop designs can extend an isolation spacing to the submicron region without a decrease in junction breakdown voltage and an increase in junction leakage current. Narrow channel effects were found to be effectively suppressed by optimum channel stop design issues.

We report on 1N branching devices for fiber-optic networks. A novel Y-pattern mask for loss reduction in branching waveguide has been investigated based on simulation. 18 branching waveguides fabricated by ion-exchange proved that the scattering loss at the branching region made with novel Y-pattern is reduced considerably. Pigtailing technique has been developed using glass fiber arrays (FAs). The fibers in FA are aligned precisely, so that all fibers can be easily and precisely put into alignment with the output ports in a branching waveguide chip at the same time. A glass plate is used for reinforcement which improves mechanical and thermal stability of the device. Reliability of packaged devices is being strongly demanded. Various reliability tests have been performed with packaged 18 branching devices and those results are presented.

Fiber-optic subscriber loops are beginning to be constructed worldwide as an infrastructure for the 21st century. Making the most of the superior transmission capabilities of optical fiber cable, high-speed and broadband services such as so-called Broadband-ISDN (B-ISDN) services are expected to be achieved. We review current trends in fiber-optic systems and discuss how fiber-optic subscriber loops should be implemented from the points of view of services and technology. First, prospective services offered over fiber-optic subscriber loops and resulting requirements for such loops are presented. Various kinds of services produced through fiber-optic subscriber loops will further develop the information-oriented society and have a major influence not only on the industrial world but on family life as well. Next, basic concepts of totally fiber-optic subscriber loops and proposals for shifting from the existing metallic cable network to totally fiber-optic subscriber loops are discussed. In this regard, we must consider the advantages of optical fiber cables and improve upon the disadvantages of the existing metallic cable network. In particular, a Digital Loop Carrier (DLC) system or a Passive Double Star (PDS) have been proposed to shift from the existing metallic cable network to totally fiber-optic subscriber loops effectively and economically. Finally, line configuration topology and latest fiber-optic technologies such as high-count cable, construction techniques and operation systems for use in achieving totally fiber optic subscriber loops are shown. We believe a single star configuration is the most appropriate for totally fiber-optic subscriber loops.