Plastic modules for free-space optical interconnects

A combined optoelectronic and optomechanical packaging technique for the construction of snap-together free-space optical interconnect systems is described. The modules integrate relaying and routing functions by use of transparent optical molded plastic, which can achieve sufficient alignment precision that further adjustment is not required during system assembly. Methods to integrate the optoelectronic chips, such as vertical-cavity surface-emitting laser and receiver arrays with these plastic optical modules are described. Other chips can also be integrated to form optoelectronic multichip modules. These modules can also be designed to accommodate coupling to or from optical fiber arrays. A test-bed system to demonstrate the concept was assembled to a lower precision by use of conventional machining techniques.     

Relay lens-free birefringence-customized stackable beam-steering modules for optical interconnects

A previously suggested birefringence-customized modular optical interconnect technique is extended for lens-free relay operation. Various lens-free relay imaging models are developed. We claim that the lens-free relay system is important in simplifying an optical interconnect system whenever the imaging conditions permit. To verify the validity of various proposed concepts, we experimentally implemented some 8 x 8 optical permutation modules. High-power efficiency and low channel cross talk were experimentally observed. In general, the larger the channel spacing, the less the cross talk. A quantitative cross-talk measurement of the lens-free relay system shows that, for a fixed channel width of 0.5 mm and channel spacings of 0.5, 1, and 2 mm, a less than -20-dB cross-talk performance can be guaranteed for lens-free relay distances of 40, 280, and 430 mm, respectively.     

Connection cube modules for optical backplanes and fiber networks

A modular free-space optical system, called the connection cube, for connecting arrays of electro-optic transceivers and fiber-array connectors is presented. The connection cube module provides bidirectional data transfer between four processing nodes on a cube face and can be used as a basic building block for optical backplanes and interconnect networks. An experimental system for connecting four processing nodes is presented and used to examine alignment and packaging issues. An analysis of the dimensional requirements and scaling capability for systems based on this module is conducted. This analysis shows that, when the connection cube module is adapted to vertical-cavity surface-emitting-laser-based point-to-point fiber-array links currently under development, it can connect up to 14 processing nodes with an aggregate data transfer capacity of 112 Gbits/s with 19.6-W power consumption.     

Cost, performance, and reliability simulator for optical transceiver modules

The program couple combines simulators for optical performance, mechanical reliability, and production cost under a graphical-user interface to design, simulate, and evaluate micro-optomechanical structures. The thermal simulator predicts the package temperature distribution on the basis of the materials and the geometry as well as on heat sources, sinks, and boundary conditions. The thermal distribution is input to the mechanical simulator, which calculates the stresses or strains and displacements caused by differential thermal expansion. The optical simulator predicts the impact on the optical efficiency and the cross talk of mechanical and optical parameter variations such as solder heights, misalignments, and wavelength distributions. The cost simulator represents the manufacturing process flow and calculates the final cost and the cost sensitivity on basis of the cost and the yield of each process step. By means of balancing detector and coupling yield, cosimulation from optical to cost domains determines the optimum detector size to produce the lowest-cost transceiver module.     

Design, implementation, and characterization of a folded spot-array generator for a modulator-based free-space optical interconnect

A folded structured light generator is presented. This spot generator is to be used in a modulator-based free-space optical interconnect. Three cascaded diffractive optical elements produce 4 x 8 clusters on an 800 microm x 1600 microm pitch, in which each cluster is a 4 x 4 array of 13.1-microm-radius spots on a 90-microm pitch. The folded configuration is more compact than an existing linear spot-array generator and replaces 14 optical surfaces with eight surfaces. Details of the optical design, sensitivity analysis, alignment techniques, assembly, and test results are presented.     

Efficient algorithm for edge cracked geometries

The stress field in a finite, edge cracked specimen under load is computed using algorithms based on two slightly different integral equations of the second kind. These integral equations are obtained through left regularizations of a first kind integral equation. In numerical experiments it is demonstrated that the stress field can be accurately computed. Highly accurate stress intensity factors and T‐stresses are presented for several setups and extensive comparisons with results from the literature are made. For simple geometries the algorithms presented here achieve relative errors of less than 10^?10. It is also shown that the present algorithms can accurately handle both geometries with arbitrarily shaped edge cracks and geometries containing several hundred edge cracks. All computations were performed on an ordinary workstation. Copyright © 2005 John Wiley & Sons, Ltd.     

Economic tolerance design for folded normal data

An important issue for design engineers is how to assign tolerance limits economically. Most work related to tolerance design is for nominal-is-best (N-type) quality characteristics and restricted by a normality assumption. However, smaller-is-better (S-type) quality characteristics and larger-is-better (L-type) quality characteristics are common in real applications. The practical distributions for S-type data or L-type data are typically skewed, and the normality assumption is violated. Determining tolerance with non-normal data using methodologies based on a normality assumption is not appropriate. This study considers the case in which measurements are recorded without their algebraic signs. The folded normal distribution works well to fit these absolute data. Based on the statistical properties of the folded normal distribution, this study develops an economic model encompassing quality loss, manufacturing costs, and re-work costs to determine tolerances. By minimising total costs, a procedure based on the Newton-Raphson method is utilised to obtain the optimal solution. Finally, a welding machine experiment is carried out to demonstrate the applicability of the proposed model.     

Non-line-of-sight single-scatter propagation model for noncoplanar geometries

In this paper, a geometrical propagation model is developed that generalizes the classical single-scatter model under the assumption of first-order scattering and non-line-of-sight (NLOS) communication. The generalized model considers the case of a noncoplanar geometry, where it overcomes the restriction that the transmitter and the receiver cone axes lie in the same plane. To verify the model, a Monte Carlo (MC) radiative transfer model based on a photon transport algorithm is constructed. Numerical examples for a wavelength of 266 nm are illustrated, which corresponds to a solar-blind NLOS UV communication system. A comparison of the temporal responses of the generalized model and the MC simulation results shows close agreement. Path loss and delay spread are also shown for different pointing directions.     

A boundary-integral formulation for complex three-dimensional geometries

A new boundary-integral formulation is proposed to analyse the heat transfer in complex three-dimensional geometries. One example of such geometry is the die sets in the injection moulding process. Networks of cooling conduits within the mould and the closely spaced die surfaces require special attention both in formulation and numerical treatment of the integral equations. The proposed formulation couples the boundary formula, the gradient of the boundary formula and the exterior formula. The derivation of the integral equations is presented here along with an efficient method for integration of some of the kernels in these equations and a semi-analytical procedure for the integration of the highly singular integrands which result from differentiating the boundary formula. Although the techniques introduced here are applied to a particular problem in heat transfer, their potential application is much broader.     

J integrals for some crack and notch geometries

Numerical values are obtained for the path independent integrals, crack opening displacements, and energies of some common crack geometries exhibiting incompressible elastic-power hardening material behavior. Displacement as well as stress formulations of the finite element method are used to discretize the problems and the solutions are obtained through nonlinear optimization. The J integral as well as its dual I are evaluated by energy differencing. The results are also applicable to steady-state creep.Plane strain/stress results are presented for tensile specimens containing center, double edge, and single edge cracks and plane strain results are given for the standard compact tension and bend specimens. Values obtained for J are generally lower than those for I. Numerical values for J are also reported for tensile specimens containing center and double edge notches with finite radius.

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Résumé On a obtenu des valeurs numériques pour des intégrales indépendantes du contour pour les déplacements d'ouverture d'une fissure ainsi que pour les énergies associées à diverses géométries communes de fissure, qui font état d'un comportement de matériaux incompressibles élastiques non linéaires. On utilise les formulations de déplacement et de contraînte de la méthode des éléments finis pour analyser le problème de manière discrète, et les solutions sont obtenues par une optimisation non linéaire. L'intérale J ainsi que l'intégrale I introduite par Bui sont évaluées en différenciant l'énergie. Les résultats sont également applicables au fluage en condition stable.Les résultats en état plan de déformation ou de tension sont présentés dans le cas d'éprouvette de traction comportant des fissures centrales, des fissures doubles latérales ou simples latérales. Des résultats en état plan de déformation sont fournis dans le cas d'éprouvettes standards compactes de traction et de flexion. On observe qu'en général les valeurs de J obtenues sont plus faibles que celles de I. Les valeurs numériques de J sont également obtenues pour les éprouvettes de traction comportant des entailles centrales ou latérales doubles de rayon fini.

     

Design and analysis of folded channels for chip-based separations

Analytical methods are employed to investigate band broadening in a microchannel turn and adjoining straight channel segments for species transport by electrophoresis or electroosmotic flow. On the basis of closed-form solutions, we find that turn-induced broadening is negligible relative to total broadening when the radius of the turn exceeds some minimum. This minimum radius is about six-tenths of the product of the channel width and the Peclet number. We also find that the minimum radius is significantly reduced when a straight channel segment adjoins the turn in a folded configuration. Such straight segments noticeably reduce the minimum radius even for segment lengths comparable to the turn radius. The application of these results to folded and spiral channels is discussed, and sample calculations for practical conditions are presented. New pleated and coiled geometries for the compact layout of separation channels are also presented.     

Selection of modules for mass customisation

Satisfying customer expectations is of paramount importance in today's markets. A customer expects to receive a product that meets as best as possible his/her expectations. To satisfy diversified requirements companies may focus on product families. For a specific customer the company has to select within a product family what will make a valid product. Then, in a just-in-time environment, the suppliers may have to provide the exact subassemblies corresponding to each product in a predefined time. This integration takes place by designing modules for the supplier. This paper proposes to extract customers’ behaviour patterns, in terms of the components required, using data-mining and entropy maximisation when selecting modules to be manufactured. Different methods for selection of modules are proposed. Computational tests are performed to evaluate performance of the selection methods with respect to the specified assembly time/resource level.     

Searching for optimal mitigation geometries for laser-resistant multilayer high-reflector coatings

Growing laser damage sites on multilayer high-reflector coatings can limit mirror performance. One of the strategies to improve laser damage resistance is to replace the growing damage sites with predesigned benign mitigation structures. By mitigating the weakest site on the optic, the large-aperture mirror will have a laser resistance comparable to the intrinsic value of the multilayer coating. To determine the optimal mitigation geometry, the finite-difference time-domain method was used to quantify the electric-field intensification within the multilayer, at the presence of different conical pits. We find that the field intensification induced by the mitigation pit is strongly dependent on the polarization and the angle of incidence (AOI) of the incoming wave. Therefore, the optimal mitigation conical pit geometry is application specific. Furthermore, our simulation also illustrates an alternative means to achieve an optimal mitigation structure by matching the cone angle of the structure with the AOI of the incoming wave, except for the p-polarized wave at a range of incident angles between 30° and 45°.     

Monolithic folded resonator for evanescent wave cavity ringdown spectroscopy

An optical resonator is characterized that employs both ultrahigh-reflective coated surfaces and total internal reflection to enable cavity ringdown spectroscopy of surfaces, films, and liquids. The monolithic folded design possesses a polarization-independent finesse that allows polarization-dependent phenomena, such as molecular orientation, to be probed. Although a restricted bandwidth (~15% of the design wavelength) results from use of reflective coatings, the resonator provides high sensitivity and facile operation. A minimum detectable absorption of 2.2 x 10(-6) was obtained for single laser shots by use of multimode excitation at 530 nm with an excimer-pumped, pulsed dye laser.     

Dioxythiophene-based polymer electrodes for supercapacitor modules

We report on the electrochemical and capacitive behaviors of poly(2,2-dimethyl-3,4-propylene-dioxythipohene) (PProDOT-Me2) films as polymeric electrodes in Type I electrochemical supercapacitors. The supercapacitor device displays robust capacitive charging/discharging behaviors with specific capacitance of 55 F/g, based on 60 μg of PProDOT-Me2 per electrode, that retains over 85% of its storage capacity after 32?000 redox cycles at 78% depth of discharge. Moreover, an appreciable average energy density of 6 Wh/kg has been calculated for the device, along with well-behaved and rapid capacitive responses to 1.0 V between 5 to 500 mV s(-1). Tandem electrochemical supercapacitors were assembled in series, in parallel, and in combinations of the two to widen the operating voltage window and to increase the capacitive currents. Four supercapacitors coupled in series exhibited a 4.0 V charging/discharging window, whereas assembly in parallel displayed a 4-fold increase in capacitance. Combinations of both serial and parallel assembly with six supercapacitors resulted in the extension of voltage to 3 V and a 2-fold increase in capacitive currents. Utilization of bipolar electrodes facilitated the encapsulation of tandem supercapacitors as individual, flexible, and lightweight supercapacitor modules.     

Optics modules for circular accelerator design

This paper is intended as a comparison paper to “Circular Machine Design Techniques and Tools” presented at this conference by Roger Servranckx. The intent here is to provide a tutorial discussion on the basic optics of circular particle accelerators for the benefit of those readers who have a fundamental knowledge of charged particle optics but do not make it their profession to design particle accelerators.We begin the tutorial by presenting the solutions of the first-order differential equations of motion for a single particle in a closed circular machine introducing the concepts of phase shift, beta functions, and the Courant-Snyder invariant. From these solutions we derive the transfer matrix between two points in the machine as a function of the phase shift and the parameters contained in the Courant-Snyder invariant.We then introduce typical optical building blocks (modules) used in circular machine designs and relate them to their characteristic transfer matrix elements, the phase shift through them, and the Courant-Snyder-Twiss parameters, β, α, and γ.Next we discuss the systematics of some elementary phase ellipse matching problems between optical modules.The report ends with a discussion of second-order optical modules and how they are used to provide the momentum bandwidth needed for the design of a typical circular machine.     

Resolvent Representation for Regular Differential Ideals

 We show that the generic zeros of a differential ideal [A]:H ^∞ _A defined by a differential chain A are birationally equivalent to the general zeros of a single regular differential polynomial. This provides a generalization of both the cyclic vector construction for system of linear differential equations and the rational univariate representation of algebraic zero dimensional radical ideals. In order to achieve generality, we prove new results on differential dimension and relative orders which are of independent interest. Received: June 13, 2001; revised version: May 2, 2002 Key words: Differential algebra, Differential primitive element, Cyclic vector, Computer algebra, Resolvent.     

Determination of stress intensity factors for Battelle Benchmark geometries

The finite element method is applied to a series of three dimensional cracked configurations as proposed at the Three Dimensional Fracture Analysis Workshop at Battelle Columbus, in 1976. Results for these cases are presented showing crack opening displacements and stress intensity factors around the crack profiles, derived using several methods, for values of Poisson's ratio equal to both 0.3 and 0.49. The semicircular crack mesh was also applied to the embedded circular crack problem, for which an analytical solution exists, and agreement within 1% and 3% was obtained for Poisson's ratio equal to 0.3 and 0.49 respectively, demonstrating the accuracy of the chosen meshes and evaluation techniques.

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Résumé On a appliqué la méthode par éléments finis à une série de configurations tri-dimensionnelles fissurées, telles que celles qui ont été proposées dans l'atelier du Battelle en 1976 sur l'analyse de la rupture à trois dimensions. Les résultats relatifs à ces cas sont présentés, et montrent les COD et les facteurs d'intensité de contrainte aux alentours de divers profils de fissure. Diverses méthodes sont utilisées pour les déterminer dans le cas de modules de Poisson égaux à 0,3 et 0,49. Une maille semi-circulaire a également été utilisée pour traiter le problème de la fissure circulaire noyée, pour lequel une solution analytique existe. On a obtenu un accord entre 1 et 3% dans le cas de rapport de module de Poisson égaux à 0,3 et 0,49 respectivement, ce qui démontre la fiabilité des mailles choisies et des techniques d'évaluation.

     

x-拟连续模

定义了Q-模及Q(x)-模,证明了M是Q-模当且仅当M是拟连续模以及给出了1型x-拟连续模和2型x-拟连续模的等价条件,并且推广了已有的一些相关的结果.