光纤光栅写入的最新进展

光纤光栅写入的发展在近年来十分迅速,各种写入法层出不穷,文中综述了光纤光栅写入技术在近一两年的最新发展     

Microstructured fibre Bragg gratings: analysis and fabrication

A microstructured fibre Bragg grating that relies on a partial and localised etching of the cladding layer along the grating region is proposed. The main effect is the formation of defect states inside the bandgap depending on surrounding refractive index. This leads to the possibility of realising novel optoelectronic devices for sensing and telecommunication applications.     

Statistical control of VLSI fabrication processes

Random fluctuations in very large scale integrated circuit (VLSIC) fabrication processes cause the parametric production yield to fall below acceptable levels, resulting in a loss of competitive edge. To address this problem, a framework for an integrated computer-aided-design-computer-aided-manufacturing (CAD-CAM) system that will enable the design, fabrication, control, and diagnosis of present and future VLSICs to be carried out profitably is proposed. It is argued that the inefficiencies of present-day CAM systems are due to the lack of appropriate methodologies for process monitoring and statistical techniques to analyze the in-process and end-of-process data. Methodologies for monitoring lots in fabrication lines, using in situ measurements, and for controlling lots, using the multivariate distribution of observable in-process parameters, are discussed. These methodologies attempt to eliminate the pitfalls of the previous statistical process control algorithms. The software system that implements the algorithms has shown encouraging results when applied to industrial fabrication lines     

Recent progress in microstructured polymer optical fibre fabrication and characterisation

Recent progress in microstructured polymer optical fibre fabrication and characterisation will be presented. A wide range of different optical functionalities can now be obtained by modifications of the microstructure, as is demonstrated by the fibres presented here. Microstructured fibres that are single-mode, highly birefringent or show twin-core coupling are described, in addition to graded-index microstructured fibres and hollow core fibres, the latter case being where light is guided in an air core. Microstructured polymer optical fibres are an exciting new development, offering opportunities to develop fibres for a wide range of applications in telecommunications and optical sensing.     

Design and fabrication of dispersion-shifted depressed-clad triangular-profile (DDT) single-mode fibre

A new depressed-clad triangular-index-profile single-mode fibre with dispersion minimum shifted to the 1.55 ?m region is investigated. Fibres with high cutoff wavelength (?1.1 ?m) and low dispersion slope (?0.052 ps/km nm2) at their minimum dispersion wavelength (?1.55 ?m) were fabricated. Results from 226.7 km of fibre show an average loss of 0.241 dB/km at 1.55 ?m and 0.232 dB/km at the loss minimum.     

Simulation of complete VLSI fabrication processes withheterogeneous simulation tools

An integrated environment for the simulation of VLSI fabrication processes is presented. Emphasis is put on automated operation to achieve maximum efficiency in TCAD deployment. Addressing the increasing number and diversity of process steps in state-of-the-art semiconductor fabrication processes, mechanisms have been devised to support the smooth, automatic interaction of heterogeneous simulation tools with multiple data formats in the context of large-scale experiments for global calibration, device optimization, and yield improvement tasks. For maximum versatility, the operation of the environment is either controlled via a graphical user interface, a batch file, or a combination of the two. It is possible to submit predefined analysis tasks for background execution, while still being able to monitor and control operation and to access and view simulation data interactively. Split-lot experiments are performed on workstation clusters in parallel operation, delivering the desired results in the shortest possible time. The TCAD environment presented offers server functionality for running large number of complex simulations. At the same time, it supports the design and seamless integration into the environment of client task applications     

Micro- and nanofabrication processes for hybrid synthetic and biological system fabrication

The application of micro- and nanofabrication processes to the development of hybrid synthetic and biological systems may enable the production of new devices such as controllable transporters, gears, levers, micropumps, or microgenerators powered by biological molecular motors. However, engineering these hybrid devices requires fabrication processes that are compatible with biological materials such as kinesin motor proteins and microtubules. In this paper, the effects of micro- and nanofabrication processing chemicals and resists on the functionality of casein, kinesin, and microtubule proteins are systematically examined to address the important missing link of the biocompatibility of micro- and nanofabrication processes needed to realize hybrid system fabrication. It is found that both casein, which is used to prevent motor denaturation on surfaces, and kinesin motors are surprisingly tolerant of most of the processing chemicals examined. Microtubules, however, are much more sensitive. Exposure to the processing chemicals leads to depolymerization, which is partially attributed to the pH of the solutions examined. When the chemicals were diluted in aqueous buffers, a subset of them no longer depolymerized microtubules and in their diluted forms still worked as resist removers. This approach broadens the application of micro- and nanofabrication processes to hybrid synthetic and biological system fabrication.     

An inorganic resist technology and its applications to LSI fabrication processes

An Ag/Se-Ge inorganic resist technology is applied to photolithographic processes in LSI fabrication. This paper describes exposure latitude, RIE characteristics, resist fabrication and exposure throughputs, pattern alignment, defocus tolerances and fabrication yields of Al interconnection.Lateral Ag diffusion does not effectively improve the exposure tolerance. The technology exhibits good compatibility with other equipment and technologies, offering satisfactory throughput. Excellent accuracy in pattern alignment is obtained owing to dry-deposition fabrication and the suitable optical properties of the Se-Ge inorganic film, which result in regulated and distinct alignment signals. Defocus tolerance in the resist is larger than that of polymer resist by 2 ∽ 3 μm in the submicron pattern. Al interconnections using this resist demonstrate a short-circuit failure rate of less than 1% and small variation in linewidth having a standard deviation of σ_w = 0.08 μm.In practical processes, the significant advantages of this resist are its bilayer resist structure (doped Ag-Se-Ge and underlying Se-Ge) and its dry deposition, very thin, favorable optical characteristics.     

Simulation of critical IC fabrication processes using advanced physical and numerical methods

Critical steps of IC fabrication are simulated by one- and two-dimensional computer programs using advanced physical models. Our codes deal with an arbitrary number of physical quantities such as concentrations of dopants, vacancies, interstitials and clusters, the electrostatic potential, and so on. Furthermore, they easily permit the exchange or variation of the physical models under consideration. As typical applications phenomena of coupled diffusion in one and two dimensions and dynamic arsenic clustering are investigated. The differences caused by the models of the zero space-charge approximation and the solution of the exact Poisson equation are studied by examples of As-B diffusion with various doping concentrations at different temperatures. A dynamic cluster model developed for the simulation of thermally annealed As implantations is compared to measured data of laser annealing experiments. A short outline of the mathematical and the numerical problems is given to show the amount of sophistication necessary for up-to-date process simulation.     

Technical and economic factors in university instructional television systems

An overview of technical and economic factors which need to be considered in university ITV systems is presented. Cost data are presented which should be useful in planning and decision making. The data can be extrapolated for at least three to five years by adding about five percent per year to all costs.     

Statistical control of VLSI fabrication processes. II. A softwaresystem

For pt.I see ibid., vol.1, no.2, p.62-71, 1988. The algorithms used to implement the CMU-CAM statistical control system for VLSI integrated circuit fabrication are presented. The CMU-CAM system performs three major operations: modeling; quality control; and feed-forward control. In order to increase the efficiency of modeling and control, the problem is decomposed using statistical factorization techniques. Algorithms for process modeling and algorithms used in quality control and feed-forward control are described. The CMU-CAM system performs profit maximization through statistical process control. Its capabilities are illustrated by a number of computational examples     

Model of high-concentration erbium-doped fibre amplifier: Effects of migration and upconversion processes

A statistical model for studying migration assisted upconversion processes in high-concentration erbium-doped fibre amplifiers is presented. Obtained theoretical results agree with experimental data for a small signal gain at 1530 nm.     

High-rate fabrication of wholly synthesised fibre preforms by the multiflame VAD method using SiHCI3 raw materials

High-rate fabrication techniques for wholly synthesised graded-index fibre preforms were developed. An overall deposition rate of 5.6 g/min was attained using a multiflame VAD burner and using SiHCl3. A low loss of 0.25 dB/km at 1.59 ?m and a small eccentricity of less than 0.4% were obtained.     

Photovoltaics in grid-connected buildings: Energy flow and economic aspects

Two main subjects must be considered in the analysis of a photovoltaic grid-connected building. the first concerns the various energy flows, such as the hourly photovoltaic generation and the electricity consumption of the building, that determine the global energy balance, i.e. the extent to which the system will be able to supply the building's electricity consumption. This paper provides a simple method to estimate this behaviour. Secondly we must consider the long-term cost of the system, a key aspect that depends on the economic scenario and can be made attractive given the appropriate policies (some examples are mentioned).     

Technical and economic impact of the use of standard-B earth stations in the intelsat system

More than 20 years after the INTELSAT system started up, satellite technology developments have led to considerable changes in the world-wide international satellite transmission system. This evolution and the present capabilities offered by digital technologies make it possible to reassess the potential cost advantages of standard-B earth stations over a wider portion of international telephone transmission routes. This paper addresses the technical and economic issues raised by the characteristics of the present and planned INTELSAT satellites, together with the current capabilities of digital techniques (forward error correction, low rate encoding, time and frequency division multiple access). The foreseeable impact of the use of such techniques on overall satellite telephone transmission costs is also presented, and compared with that forecasted for fibre optic cable circuits.     

Application of two-dimensional process/device simulation for evaluating MOSFET fabrication processes

Applications of a two-dimensional process/device simulator are presented for evaluating the fabrication conditions of MOSFETs. By comparing the simulated results with the measured values, variations in the fabrication sequence have been found. In the analytical mode, a checkup flow is proposed for determining anomalous device structure parameters, such as channel length and gate-oxide thickness. For optimization, the main cause of fluctuating device performance is found automatically. The simulation results confirm that both analysis and optimization modes are effective for identifying variations in the fabrication conditions.     

Refinements of fabrication processes in sputtered double-layer ITO/InP solar cells

A two-layer fabrication technique developed to avoid surface degradation in sputtered indium tin oxide (ITO)/indium phosphide (InP) solar cells, initially provided insight into junction formation mechanisms, and has now been further refined to provide gains in efficiency. A critical parameter is the deposition rate of the first layer (indium tin) onto the InP surface, and it was found that this layer should be deposited at greater than 1Ås^?1. A major problem was the series resistance and, to improve this, extensive experimental work was carried out into varying the post-deposition annealing procedure of the second film, the ITO layer. Finally, a preliminary study of devices with the first layer electron-beam evaporated was carried out and a comparison between sputtered and electron-beam devices confirmed previous ideas on junction formation mechanisms.     

Large area dye‐sensitized solar cells: material aspects of fabrication

Dye‐sensitized photoelectrochemical solar cells of large area are fabricated using highly conducting and optically transparent glass consisting of an inner layer of indium‐tin oxide and an outer layer of fluorine doped tin oxide. A method is described for the deposition of nanocrystalline films of TiO₂ consisting of large and small median size particles (30 and 5 nm, respectively) which promote porosity and light scattering. Incorporation of trace quantities of magnesium oxide into TiO₂ increased the efficiency of the cells. The energy conversion efficiency of a cell (AM 1·5, 1000 W m⁻² simulated sunlight) of area 21 cm² was found to be 7·2% compared to 5·6% in the absence of magnesium oxide. The mechanisms by which the magnesium oxide improves the cell performance are discussed. Copyright © 2006 John Wiley & Sons, Ltd.