Broadband and compact 2-D photonic crystal reflectors with controllable polarization dependence

Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors (experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50/spl times/50 /spl mu/m/sup 2/) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.     

Stability of linear time-delay systems

The sufficient condition of stability of linear system with delay in the form of frequency equality is received. Efficiency of the received criterion is shown on examples.     

Integrated thermal-fluidic I/O interconnects for an on-chip microchannel heat sink

Power dissipation in microprocessors will reach a level that necessitates chip-level liquid cooling in the near future. An on-chip microfluidic heat sink can reduce the thermal interfaces between an IC chip and the convective cooling medium. Through wafer-level processing, integrated thermal-fluidic I/O interconnects enable on-chip microfluidic heat sinks with ultrasmall form factor at low-cost. This letter describes wafer-level integration of microchannels at the wafer back-side with through-wafer fluidic paths and thermal-fluidic input/output interconnection for future generation gigascale integrated chips.     

Aspects of 5-alpha reductase deficiency, a review

Two forms of 5 alpha-reductase deficiency have been described and two genes have been cloned. In view of the psychoendocrinological complexity of the primary form, the early diagnosis preferably in infancy, is crucial. Rearing up those who are assigned as females to the male gender identity could minimize the risk of gender identity and role disorders when puberty is reached.     

Interface-related reliability challenges in 3-D interconnect systems with through-silicon vias

During service, through-silicon vias (TSVs) in vertically stacked-die microelectronic packages are subjected to both thermo-mechanical cycling as well as electromigration. The disparate properties of Cu-filled TSVs and the Si chip induce substantial residual stresses in both components, as well as at the interface. These stresses may drive interfacial sliding with the interface serving as a rapid diffusion path, resulting in significant interfacial strain incompatibilities. In addition, by acting as short-circuit paths for diffusion, the interfaces may carry significant electromigration fluxes, further exacerbating interfacial sliding. The results of recent experiments and modeling are presented to illustrate these effects, and related reliability issues are discussed.     

InP bonded membrane photonics components and circuits: toward 2.5 dimensional micro-nano-photonics

The general objective of this presentation is to demonstrate the great potential of III-V semiconductor -membrane photonic devices, with a special emphasis on InP and related materials in the prospect of new developments in the field of micro-nano-photonics. Various classes devices will be presented, which will have the communality of being based on the use of high index contrast structuration of semiconductor materials. The structuration is achieved vertically for the first class, by forming thin semiconductor membranes surrounded by low optical index material, or laterally for the second class via a two-dimensional (2-D) lateral structuration of the membranes (thus, resulting in 2-D photonic crystal (PC) structures); both structurations are also combined, according to a "2.5-dimensional" approach, which should broaden considerably the combinations of functionality beyond those presently contemplated with the two first classes. The general technological scheme of the membrane approach is fully compatible with planar technology which is widely in use in the world of silicon microelectronics and with heterogeneous integration of III-V active microphotonic devices with silicon microphotonics and microelectronics (e.g., molecular bonding of InP active membranes on silica on silicon substrate). A variety of devices will be presented, featuring micro-lasers based on 2-D PC micro-cavities as well as on 2-D Bloch modes (2-D distributed-feed-back micro-laser) for in plane and surface emission.     

A Quality Control Chart for Work Performance Appraisal

A substantial disagreement between total quality management/Deming's principles and traditional management falls in the area of work performance appraisal. In fact, Deming ranks the traditional “evaluation of performance, merit rating, or annual review” third in his list of the Seven Deadly Diseases of the western style of management. Deming advocates argue that many of the faulty management practices in performance appraisal originate from a failure to understand variation among workers and a failure to distinguish between the “common causes” and the “special causes” of variation. Deming emphasized quality control charts as a proper tool for monitoring the stability of a system, for distinguishing the special causes from the common causes, and for detecting who among the workers is performing within the system, out of the system on the good side, or out of the system on the poor side. However, the implementation of most control charts requires that the performance ratings be quantitative on the interval scale of measurement, which may not be the case in practice. Some merit systems use ratings that are only categorical on the ordinal scale of measurement (e.g., excellent, good, fair, and poor) or rank workers by arranging them in order of merit from 1, 2, last.

Deming, however, did not show how to construct a control chart for performance appraisal when the performance ratings are reported only on the ordinal scale of measurement. In this article, we propose a quality control chart that is particularly useful in the area of performance appraisal when the workers' ratings are categorical on the ordinal scale of measurement. The proposed chart can aid managers in implementing Deming's teachings on performance appraisal. The manager will then be able to understand variation among workers and to distinguish between the “common causes” and the “special causes” affecting a certain work system. The manager can then determine who among the workers is performing within the bounds of the system, out of the system on the good side, or out of the system on the poor side.     

Compact 1.55 /spl mu/m room-temperature optically pumped VCSEL using photonic crystal mirror

Reported is the first realisation of a novel vertical cavity surface emitting laser (VCSEL), in which one of the Bragg mirrors is entirely replaced by a single-layer photonic crystal mirror (PCM). The presence of the PCM considerably enhances the vertical compactness of the device. Room-temperature singlemode laser emission has been obtained at 1.55 mum by optical pumping (pulsed regime), with a threshold power around 15 mW     

The behaviour of a trickle tower electrolytic cell for the production of cobalt(III) acetate from cobalt(II) acetate

The production of Co(III) acetate from Co(II) acetate using a bipolar trickle tower of graphite Raschig rings was investigated. Space time yields up to 18 kg m^–3 h^–1 were obtained, which showed no improvement over those achievable in a conventional plate and frame cell. A mathematical model of the system indicated that the electrode reactions occurred almost entirely at the opposing annular surfaces between consecutive layers of Raschig rings and that the unexpectedly low performance of the device was most probably due to the unfavourable mass transport conditions which existed in the intervening gaps.Nomenclature a annular cross sectional area of one Raschig ring (m²) - b _C kinetic exponential constant for reduction of Co(III) (V^–1) - b _A kinetic exponential constant for oxidation of Co(II) (V^–1) - b _H kinetic exponential constant for hydrogen evolution (V^–1) - b ₀ kinetic exponential constant for oxygen evolution (V^–1) - [Co(II)] concentration of Co(II) (mol m^–3) - [Co(III)] concentration of Co(III) (mol m^–3) - F Faraday constant (96 487 C mol^–1) - f fraction of total flow by-passing the annular gap between adjacent Raschig rings in a vertical row - I current per vertical column of rings (A) - k _C rate constant for reduction of Co(III) (A m mol^–1) - k _A rate constant for oxidation of Co(II) (A m mol^–1) - k _H rate constant for hydrogen evolution (A m^–2) - k _O rate constant for oxygen evolution (A m^–2) - k _L mass transfer coefficient (m s^–1) - Q flow rate per vertical row of Raschig rings (m³s^–1) - v volume of annular gap between adjacent Raschig rings in a vertical row (m³) - V superficial velocity of electrolyte (m s^–1) - _A anodic potential (V) - _C cathodic potential (V)