Potential light source for photonic integrated circuits based on the equilateral triangle resonator

The semiconductor microlasers based on the equilateral triangle resonator (ETR) can be fabricated from the edge-emitting laser wafer by dry-etching technique, and the directional emission can be obtained by connecting an output waveguide to one of the vertices of the ETR. We investigate the mode characteristics, especially the mode quality factor, for the ETR with imperfect vertices, which is inevitable in the real technique process. The numerical simulations show that the confined modes can still have a high quality factor in the ETR with imperfect vertices. We can expect that the microlasers is a suitable light source for photonic integrated circuits.

Polarization switching current of vertical cavity surface-emitting Lasers in an applied electric field

The polarization of vertical-cavity surface-emitting laser (VCSEL) can be controlled by electro-optic birefringence. We calculated the birefringence resulted from external electric field which was imposed on the top DBR of VCSEL by assuming that the two polarization modes were in the same place of the gain spectra in the absence of electric field beginning. By modifying SFM, the affection of the electric field strength on the polarization switching currents between the two polarization modes had been shown.

Ti Schottky barrier diodes on n-type 6H-SiC

Using thermal evaporation, Ti/6H-SiC Schottky barrier diodes (SBD) were fabricated. They showed good rectification characteristics from room temperature to 200degreesC. At low current density. the current conduction mechanism follows the thermionic emission theory. These diodes demonstrated a low reverse leakage current of below 1 X 10(-4)Acm(-2). Using neon implantation to form the edge termination, the breakdown voltage was improved to be 800V. In addition. these SBDs showed superior switching characteristics.

Silicon: the promising material for phontonic integrated circuits platform

The development of optical network demands integrated arid multiple functionality modules to lowing cost and acquire highly reliability. Among the various contender materials to be photonic integrated circuits platform, silicon exhibits dominant characteristics and is the most promising platform materials. The paper compares the characteristics of some candidate materials with silicon and reviews recent progress in silicon based photonic integration technology. Tile challenges to silicon for optical integration for optical networking application arc also indicated.

Multiple quantum well self electro-optic effect devices for optoelectronic smart pixels

The investigations on GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays for optoelectronic smart pixels are reported. The hybrid integration of GaAs/AlGaAs multiple quantum well devices flip-chip bonding directly over 1 mu m silicon CMOS circuits are demonstrated. The GaAs/AlGaAs multiple quantum well devices are designed for 850nm operation. The measurement results under applied biases show the good optoelectronic characteristics of elements in SEED arrays. The 4x4 optoelectronic crossbar structure consisting of hybrid CMOS-SEED smart pixels have been designed, which could be potentially used in optical interconnects for multiple processors.

An analysis of the performance of a new high-speed single-way analog switch

This paper introduces a new highspeed single-way analog switch which has both highspeed high-resolution mono-direction analog transmission gate function and high-speed digital logic gate function with normal bipolar technology. The analysis of static and transient switching performances as an analog transmission gate is emphasized in the paper. In order to reduce the plug-in effect on high-speed high-resolution systems, an optimum design scheme is also given. This scheme is to achieve accelerated dynamic response with very low bias power dissipation. The analysis of PSPICE simulation as well as the circuit test results confirms the feasibility of the scheme. Now, the circuit has been applied effectively to the designs of novel highspeed A/D and D/A converters.

Electrically-controlled near-infrared chiroptical switching of enantiomeric dinuclear ruthenium complexes

Enantiomerically pure dinuclear ruthenium complexes with 1,2-dicarbonylhydrazide as a bridging ligand are optically active in the visible and near infrared spectral regions depending on the oxidation states of the metal centers and are useful as an electrochemically driven near infrared chiroptical switch.

Networks with hexagonal circuits in co-ordination polymers of metal ions (Zn-II, Cd-II) with 1,1 '-(1,4-butanediyl)bis(imidazole)

Three new compounds, [ZnL1.5(H2O)(SO4)]. 6H(2)O 1, [ZnL1.5(H2O)(2)][NO3](2). 2H(2)O 2 and [CdL1.5(H2O)(2)(SO4)]. 4H(2)O 3 were obtained from self-assembly of the corresponding metal salts with 1,1'-(1,4-butanediyl)bis(imidazole) (L). In both 1 and 2 zinc ion is five-co-ordinated, showing a less-common trigonal bipyramidal co-ordination polyhedron, while cadmium ion of 3 is six-co-ordinated with a common octahedral arrangement. The sulfate ions of 1 and 3 are co-ordinated, however the nitrate ions of 2 are not. Each of the three compounds is composed of a (6, 3) network with the hexagonal smallest circuit containing six metal ions and six L; each L is co-ordinated to two metal ions, acting as a bridging ligand. In 1 the 2-D sheet of (6, 3) networks is interpenetrated in an inclined mode by symmetry related, identical sheets to give an interlocked 3-D structure, while the (6, 3) networks of both 2 and 3 stack in a parallel fashion to construct frameworks having channels.

Column switching-back flushing technique for the analysis of aromatic compounds in gasoline

A simple method, based on the technique of capillary column switching-back flushing, has been developed for the detailed analysis of aromatic compounds in gasoline. The sample was first separated on a 30-m long OV-2330 polar precolumn and then backflushed onto a nonpolar analytical column. The early eluting components from the precolumn and the components of interest (aromatic compounds plus heavier compounds) eluting from the analytical column are all directed to the same flame ionization detection system through a T piece, which permits the quantitative analysis of aromatic hydrocarbons in gasoline by a normalization method using correcting factors. The switching time window of the method is +/-5 s, resulting in easier operation and higher reliability. The reproducibility of the quantitative analysis was less than or equal to3% RSD for real gasoline samples. (C) 2002 Elsevier Science B.V. All rights reserved.

Qualitative Analysis of MOS Circuits

With the push towards sub-micron technology, transistor models have become increasingly complex. The number of components in integrated circuits has forced designer's efforts and skills towards higher levels of design. This has created a gap between design expertise and the performance demands increasingly imposed by the technology. To alleviate this problem, software tools must be developed that provide the designer with expert advice on circuit performance and design. This requires a theory that links the intuitions of an expert circuit analyst with the corresponding principles of formal theory (i.e. algebra, calculus, feedback analysis, network theory, and electrodynamics), and that makes each underlying assumption explicit.

Flexibility and Efficiency in a Computer Program for Designing Circuits

This report is concerned with the problem of achieving flexibility (additivity, modularity) and efficiency (performance, expertise) simultaneously in one AI program. It deals with the domain of elementary electronic circuit design. The proposed solution is to provide a deduction-driven problem solver with built-in-control-structure concepts. This problem solver and its knowledge base in the applicaitn areas of design and electronics are descrbed. The prgram embodying it is being used to explore the solutionof some modest problems in circuit design. It is concluded that shallow reasoning about problem-solver plans is necessary for flexibility, and can be implemented with reasonable efficiency.

Switching Between Discrete and Continuous Process Models to Predict Molecular Genetic Activity

Two kinds of process models have been used in programs that reason about change: Discrete and continuous models. We describe the design and implementation of a qualitative simulator, PEPTIDE, which uses both kinds of process models to predict the behavior of molecular energetic systems. The program uses a discrete process model to simulate both situations involving abrupt changes in quantities and the actions of small numbers of molecules. It uses a continuous process model to predict gradual changes in quantities. A novel technique, called aggregation, allows the simulator to switch between theses models through the recognition and summary of cycles. The flexibility of PEPTIDE's aggregator allows the program to detect cycles within cycles and predict the behavior of complex situations.