Based on the partially-depleted, thin-film SOI/CMOS technology, the influence of reduced junction capacitance on the performance of the elementary gates and large scale gate array chip is reviewed. To further reduce the power consumption, SOI-specific device configurations, in which the body-bias is individually controlled, are effective in lowering the supply voltage and hence the power consumption while keeping the circuit speed. Two attempts are introduced: (1) DTMOS (Dynamic-Threshold MOS)/SOI to achieve ultra low-voltage and yet high-speed operation, and (2) ABB (Active-Body-Bias) MOS to enhance the current drive under the low supply voltage.

A photon-induced waveguide (PIG) for all-optical switching and wavelength conversion with the functionalities of regeneration and reshaping is proposed. Optical signals are used to switch between lateral optical wave guiding and antiguiding effects. A transfer-matrix method was developed to consider not only the variation of optical signal power along the waveguide, but also the spatial distributions of refractive index and optical confinement factor to explain the switching scheme between guiding and antiguiding. Theoretical analyses show that a threshold-like and sharp input-output response of PIG allows enhancement of the extinction ratio, reshaping, and thus enlargement of noise margin of optical signals in digital all-optical switching and wavelength conversion.

A first-order investigation of the transport and energy-loss processes in silicon dioxide is worked out in the frame of the Spherical-Harmonics solution of the Boltzmann Transport Equation. The SiO2 conduction band is treated as a single-valley spherical and parabolic band. The relevant scattering mechanisms are modeled consistently: both the polar and nonpolar electron-phonon scattering mechanisms are considered. The scattering rates for each contribution are analyzed in comparison with Monte Carlo data. A number of macroscopic transport properties of electrons in SiO2 are worked out in the steady-state regime for a homogeneous bulk structure. The investigation shows a good agreement in comparison with experiments in the low-field regime and for different temperatures.

Appropriate meshes are crucial for accurate and efficient 3D process simulation. In this paper, we present a set of tools operating on surface and interface triangulations. These tools allow the improvement of the accuracy of interfaces, the reduction of the number of triangles, and the removal of obtuse not coplanarily compensated triangles. The first tool is used within integrated topography simulation environments based on different data structures, e.g. cell-based and segment-based. The latter two are particularly important for providing appropriate input to mesh generation for 3D process simulation.

Recently, we developed a low power consumption and small total capacitance switched-capacitor filter using a single operational amplifier. It is called a semi-parallel cyclic type (SPCT) filter, in which each capacitance is in proportion to the square root of a transfer function coefficient value. In this paper, we propose the SPCT filter using a single unity gain buffer (UGB). It will be referred to a UGB-SPCT filter. It is possible to use the UGB-SPCT filter over a wider frequency range than the SPCT filter since a UGB has nearly unity gain over a wide frequency range.

Layer-by-layer sequential adsorption process of polyelectrolytes had conventionally been used for the fabrication of the ultra-thin organic film formed by various polymers with different polarity of charge. In this study, hydrophobic Ruthenium complex monomer (tris (bilyridyl) ruthenium (II) hexafluorophosphate) was micelle-wrapped with an anionic surfactant, sodium dodecylbenzenesulfonate, and was assembled with PAH (poly (allylamine hydrochloride)) which has the opposite charge on ITO substrates. With this method, we succeed in fabricating ultra-thin organic films even when the adsorption material is not polymer but monomer. Moreover it was found that the bilayer thickness of the self-assembled (Ru micelle/PAH) was systematically changed by adjusting the solution pH of each bath. By using this process, EL device was fabricated by depositing the thin film of micelle-wrapping ruthenium complex monomer on ITO and formed Bi electrode on top of the film. Light emission was observed by applying voltage to this device.

Micropatterning of organosilane self-assembled monolayers (SAMs) was demonstrated on the basis of photolithography using an excimer lamp radiating vacuum ultra-violet (VUV) light of 172 nm in wavelength. This lithography is generally applicable to micropatterning of organic thin films including alkyl and fluoroalkyl SAMs, since its patterning mechanism involves cleavage of C-C bonds in organic molecules and subsequent decomposition of the molecules. In this study, SAMs were prepared on Si substrates covered with native oxide by chemical vapor deposition in which an alkylsilane, that is, octadecyltrimethoxysilane [CH3(CH2)17Si(OCH3)3, ODS] or a fluoroalkylsilane, that is, 1H, 1H, 2H, 2H-perfluorodecyltrimethoxy-silane [CF3(CF2)7CH2CH2Si(OCH3)3, FAS] were used as precursors. Each of these SAMs was photoirradiated through a photomask placed on its surface. As confirmed by atomic force microscopy and x-ray photoelectron spectroscopy, the SAMs were decomposed and removed in the photoirradiated area while the masked areas remained undecomposed. A micropattern of 2 µm in width was successfully fabricated. Furthermore, microstructures composed of two different SAMs, that is, ODS and FAS, were fabricated as follows. For example, an ODS-SAM was first micropatterned by the VUV-lithography. Since, the VUV-exposed region on the ODS-SAM showed an affinity to the chemisorption of organosilane molecules, the second SAM, i. e. , FAS, confined to the photolithographically defined pattern was successfully fabricated. Due to the electron negativity of F atoms, the FAS covered region showed a more negative surface potential than that of the ODS surface: its potential difference was ca. 120 mV as observed by Kelvin probe force microscopy.

Simultaneous wavelength conversion of multi-WDM channels is expected to be a key technique in near-future networks. In this paper, 4-channel wavelength conversion using four-wave mixing (FWM) in a hybrid wavelength selector is successfully demonstrated. The wavelength selector consists of two four-channel spot-size-converter-integrated semiconductor optical amplifier (SS-SOA) gate arrays on a planar-lightwave-circuit (PLC) platform and two PLC-arrayed-waveguide-gratings (AWGs). As the wavelength selector has an individual SS-SOA for the wavelength conversion of each channel, there is negligible interference between channels. Four WDM channels with an 2.5 Gb/s modulation were converted from 1555 to 1575 nm. Clear eye openings and only a small power penalty of less than 0.5 dB were observed. The receiver sensitivity was -31 dBm at a bit error rate (BER) of 10-9.

This paper presents an efficient method to derive the first passage time of an extended stochastic Petri net by simple algebraic operations. The reachability graph is derived from an extended stochastic Petri net, and then converted to a timed stochastic state machine which is a semi-Markov process. The mean and the variance of the first passage time are derived by algebraic manipulations with the mean and the variance of the transition time, and the transition probability for each transition in the state machine model. For the derivation, three reduction rules are introduced on the transition trajectories in a well-formed regular expression. An efficient algorithm is provided to automate the suggested method.

Continuous-wave operation at room-tempera-ture has been demonstrated for InGaN multi-quantum-well (MQW) laser diodes (LDs) grown on FIELO GaN substrates with a backside n-contact. This was made possible by introducing important new concept of reducing threading dislocations that occur during the growth of the GaN substrates. We found that InGaN active layers grown on FIELO GaN are superior to those grown on conventional sapphire substrates in terms of their growth mode and the resultant In compositional fluctuation. The fabricated laser diode shows the threshold current, the threshold current density and the threshold voltage were 36 mA, 5.4 kA/cm2 and 7.5 V, respectively, with the lasing wavelength of 412 nm and internal quantum efficiency as high as 98%.

Optical transverse-mode properties of the GaN-based semiconductor laser-diode is characterized by effective refractive index method. In order to stabilize a transverse-mode in the conventional ridge-waveguide structure, very precise control of ridge-height is found to be necessary. On the contrary, a novel 2-step grown structure with 2-dimensional index guiding has wide feasibility for device parameter, excellent stability of large confinement factor in transverse-mode, and small aspect ratio of beam divergence, under the condition that AlN molar fraction of 0.08 in AlGaN current blocking layer and stripe width of 1.5 µm are used.

A reliable and automatic parameter extraction technique for DFB lasers is developed. The parameter extraction program which is named "LAPAREX" is able to determine many device parameters from a measured sub-threshold spectrum only, including gain- and index-coupling coefficients, and spatial phases of the grating at front and rear facets. Injection current dependence of coupling coefficients in a gain-coupled DFBlaser is observed, for the first time, by making use of it.

For NP-hard combinatorial optimization problems, approximation algorithms with high performances have been proposed. In many of these algorithms, mathematical programming techniques have been used and proved to be very useful. In this survey, we present recent mathematical programming techniques as well as classic fundamental techniques, by showing how these techniques are used in designing high-quality approximation algorithms for NP-hard combinatorial optimization problems.

A directly modulated LED or SLD (super luminescent diode) is attractive for low-cost lightwave systems such as access networks. This letter experimentally studies a directly modulated SLD followed by a gain-saturated semiconductor optical amplifier (SOA), and shows that the modulation rate is expanded in effect by the use of the gain-saturated SOA. This results from the shortened response time of the SLD due to the ASE light from the SOA and a level-equalizing effect in the gain-saturated SOA.

Maximum Satisfiability Problem (MAX SAT) is one of the most natural optimization problems. Since it is known to be NP-hard, approximation algorithms have been considered. The aim of this survey is to show recent developments of approximation algorithms for MAX SAT.

Relating to the radiated emission sources finding method based on CISPR emission measurement system, which uses only amplitude data without phase data, the applicability to horizontally polarized sources was studied. We experimentally verified by using two spherical dipole antennas as ideal emission sources in the frequency range from 300 MHz to 1GHz. As the results, the position estimation deviation Δd was less than 0.09 m, the amplitude estimation deviation Δj was less than 1.5 dB, in which position estimation accuracy was raised so much compared with that for vertically polarized sources, and additionally the angle of its horizontal current direction could be estimated. Furthermore, it was revealed that this method can be also applied even when several sources exist, consequently the applicability of this method has been greatly expanded.

An optical magnetic field measuring system using diluted magnetic semiconductors (DMS) probes is presented. The attractive features of DMS for building current/ magnetic field sensors are outlined. The system configuration includes a common-mode noise rejection scheme (CMR) to eliminate optic intensity noise induced in the fibre links by environmental vibrations. The CMR scheme relies on a pulse delay method based on the creation of two relatively delayed replicas of the photodetector output signal and their subsequent subtraction (division). Theoretical and experimental analyses of the system operation are developed and noise rejection methods using subtraction and division are presented and compared. Although CMR by division seems to be more appealing from the theoretical viewpoint (due to the rejection of intensity noise caused both by environmental vibrations and laser source output power fluctuations), in practical terms the subtraction is more reliable and easier to implement. The noise rejection figure measured experimentally is about 17 dBV for CMR both by subtraction and by division. A system calibration curve is presented. The minimum magnetic flux density detected with the system is 0.06 mT rms.

An optical fiber humidity sensor was fabricated forming a nanometer-scale Fabry-Perot interferometer by using the Ionic Self-Assembly Monolayer (ISAM) method. The materials used were Poly R-478 and poly(diallyldimethyl ammonium chloride). Taking advantage of the precision that the ISAM method can achieve in controlling the length of the nano cavity, the length was fit to obtain a maximum variation of 8.7 dB of reflected optical power between 11.3% and 85% RH. The sensor exhibited a fast response time and was able to monitor the human breathing.

The operation of a novel all-optical wavelength converter based on directionally-coupled semiconductor optical amplifiers is described. Merits such as extinction enhancement and digital response are expected through a simple analytical model and a sophisticated transfer matrix method developed to take into account the spatial distributions of the optical power, carrier density, refractive index, propagation constant, and coupling coefficient along device. We fabricated devices operating at 1.55 µm band using an InGaAsP/InP material system and demonstrated successfully the static characteristics of wavelength conversion with the expected advantages. Devices are as small as 1.5 mm and do not need any active/passive integration step during fabrication.

This paper presents a robust and nonblocking group membership protocol for large-scale distributed systems. This protocol uses the causal relation between membership-updating messages (i. e. , those specifying the adding and deleting of members) and allows the messages to be executed in a nonblocking manner. It differs from conventional group membership protocols in the following points: (1) neither global locking nor global synchronization is required; (2) membership-updating messages can be issued without being synchronized with each other, and they can be executed immediately after their arrival. The proposed protocol therefore is highly scalable, and is more tolerant to node and network failures and to network partitions than are the conventional protocols. This paper proves that the proposed protocol works properly as long as messages can eventually be received by their destinations. This paper also discusses some design issues, such as multicast communication of the regular messages, fault tolerance and application to reliable communication protocols (e. g. , TCP/IP).