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The polarization dependence of directional couplers (DC) formed by silicon-on-insulator (SOI) slot waveguides was studied, and its applications as highly efficient polarization beam splitters (PBSs) and polarization-independent directional couplers (PIDCs) were investigated. The coupling lengths for the quasi-TE and quasi-TM modes may vary with the waveguide geometry due to structural birefringence; thus numerical simulations of the coupling effects in the directional couplers with different aspect ratios and waveguide spacing were conducted to obtain the optimal design parameters for high efficiency as well as compact device size. The lengths of the coupling regions of the designed PBS and PIDC are 47.61 and 23.13 [micro]m, respectively, and they delivered good performance, with an extinction ratio greater than 20 and 1 dB bandwidth larger than 100 nm. The tolerance of fabrication error in the practical device is also discussed. [c] 2010 Optical Society of America OCIS codes: 060.1810, 130.3120, 130.5440.

We show, to the best of our knowledge, the first simulation result of the strong plasmonic field coupling and enhancement at the Ag/Si interface of a silver core/protruded silicon shell nanocylinder by using the finite-element method. The strong plasmon field, with a slow effective phase velocity accumulated at the Ag/Si interface, which results from the large effective index of the surface plasmon due to the nearly identical real parts with opposite signs of the permittivities of silver and silicon at 633 nm, is analyzed. When the silicon shell has shallow protrusions of proper periodicity to meet the phase matching condition between the incident light and the surface plasmon wave at the Ag/Si interface, a higher scattered electric field and a higher sensitivity to the refractive index change of the surrounding medium can be achieved. Furthermore, a feasible implementation of the core-shell nanocylinder design concept is studied and discussed. OCIS codes: 240.6680, 250.5403.

A hexagonal nanostructure formed by seven core shell nanocylinders filled with different dielectric cores is investigated. The surface plasmon resonance in such a hexagonal nanostructure under conditions of different illumination wavelengths, dielectric cores, angles of incidence, and thicknesses of silver shells is studied by use of the finite element method. Simulation results show that the resonant wavelength is redshifted as the dielectric constant and the size of the core increase. The peak resonant wavelength and the local field enhancement are approximately proportional to the radius of the dielectric core. Additionally, the surface plasmon field excited by TM-polarized light at the incident angle of [theta] = 15[degrees] is exactly a linear combination of those excited at incident angles of [theta] = 0[degrees] and 30[degrees], confirming the linear nature of the surface plasmon resonance in a nanostructure formed by linear media. OCIS codes: 240.6680, 250.5403.

This article identifies key features of the strategy concept as a basis for reviewing existing theories of strategy. It also provides an agenda for future research. The article argues that there is a decision hierarchy in a firm, and defines strategy as the highest-level decision in the hierarchy. Consequently, strategy has to exhibit what may be called three features of dominance: vertical dominance, horizontal dominance, and dynamic dominance. A vertically dominant strategy is one that determines, directly or indirectly, other decisions of a firm. A horizontally dominant strategy seeks to optimize the value of the firm according to some criteria. Dynamic dominance implies that strategy should affect the subsequent decisions of a firm over a relevant period of time. With few exceptions, existing theories of strategy are issue-oriented and focus largely on horizontal dominance. More research should, therefore, be directed towards vertical and dynamic dominance criteria. If a comprehensive theory of strategy which satisfies the three dominance features cannot be developed, it is suggested that development should be directed towards integrating behavioural and economic approaches. (Reprinted by permission of the publisher.)

A study was done to analyze joint ventures of multinational corporations when they serve a host market. Models were constructed to evaluate the effects of profit sharing, cost reductions, risk reductions and competition reductions on the profits from such ventures. The models show that multinational corporations from joint ventures when there is strong competition and operational risks are present. The level of significant costs determine the choice between mutinational corporations and subsidiaries. Finally, multiple licensing is done when there are many local companies.

A study was done to analyze the theoretical development of strategic groups. Theories of spatial competition and cognitive taxonomies were applied to competing strategic groups. The validity of strategic groups is questioned because since such groups are ideal, firms should not act differently. Another criticism against strategic groups is that firms which have different strategies will not be grouped effectively. Results show that strategic groups are not merely tools of analysis but are theoretically possible.

Any technological innovation changes the economic market and consequently, firm competition. Optimal timing should be considered before firms react to technological change because it may have adverse effects in the long run. Continuous technological improvement creates and changes asymmetry between firms. Strategy planners should weigh the advantages and disadvantages of technological investments in choosing whether to replace or retain existing technology.

Various production-related methods used by firms for gaining entry to foreign markets are analyzed to determine the profits firms earn by using the strategies. The entry techniques analyzed include exclusive licensing, foreign direct investment, and joint venture. Results indicate that an entering firm may be able to alter licensing charges, but the best and most popular profit-generating method is foreign direct investment.

The significance of escalating commitment to strategy formulation is discussed. Behavioral explanations of escalating commitment to a losing strategy are examined, and an economic theory of the escalating commitment phenomenon is proposed. Economic justifications for escalating commitment to a failing strategy are shown mathematically. The strategic implications of the escalating commitment phenomenon for the first-move advantage and for heavy industries in the US are discussed.

Research is presented concerning the use of data from the US insurance industry to investigate the relationship between the dynamics of strategic maneuvering, evolutionary economics and hypercompetition.