Browsing by Subject "Gates (transistor)"

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    Analytical model of asynchronous shared-per-wavelength multi-fiber optical switch
    (IEEE, 2011) Akar, Nail; Raffaelli, C.; Savi, M.
    In this paper, a buffer-less shared-per-wavelength optical switch is equipped with multi-fiber interfaces and operated in asynchronous context. An analytical model to evaluate loss performance is proposed using an approximate Markov-chain based approach and the model is validated by simulations. The model is demonstrated to be quite accurate in spite of the difficulty in capturing correlation effects especially for small switch sizes. The model is also applied to calculate the number of optical components needed to design the optical switch according to packet loss requirements. The impact of the adoption of multiple fiber interfaces is outlined in terms of the remarkable saving in the number of wavelength converters employed, while increasing at the same time the number of optical gates needed by the space switching subsystem. The numerical results produced are a valuable basis to optimize overall switch cost. © 2011 IEEE.
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    Band alignment issues in metal/dielectric stacks: a combined photoemission and inverse photoemission study of the HfO 2/Pt and HfO 2/Hf systems
    (Electrochemical Society, 2004) Sayan, S.; Bartynski, R.A.; Robertson J.; Suehle, J. S.; Vogel, E.; Nguyen, N. V.; Ehrstein, J.; Kopanski, J. J.; Süzer, Şefik; Holl, M. B.; Garfunkel, E.
    We have studied the HfO 2/Hf and HfO 2/Pt systems by photoemission and inverse photoemission spectroscopies. It is found that the "effective workfunction" of metals in multilayer structures are different than their vacuum workfunctions and are modified by their interface dipoles at the metal/high-k interface. The effective workfunction of Hf is 4.4 eV whereas that of Pt is 5.3 eV, within the range of acceptable values for PMOS and NMOS respectively.
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    State aggregation-based model of asynchronous multi-fiber optical switching with shared wavelength converters
    (Elsevier, 2013) Akar, N.; Raffaelli, C.; Savi, M.
    This paper proposes new analytical models to study optical packet switching architectures with multi-fiber interfaces and shared wavelength converters. The multi-fiber extension of the recently proposed Shared-Per-Input-Wavelength (SPIW) scheme is compared against the multi-fiber Shared-Per-Node (SPN) scheme in terms of cost and performance for asynchronous traffic. In addition to using Markov chains and fixed-point iterations for modeling the mono-fiber case, a novel state aggregation technique is proposed to evaluate the packet loss in asynchronous multi-fiber scenario. The accuracy of the performance models is validated by comparison with simulations in a wide variety of scenarios with both balanced and imbalanced input traffic. The proposed analytical models are shown to remarkably capture the actual system behavior in all scenarios we tested. The adoption of multi-fiber interfaces is shown to achieve remarkable savings in the number of wavelength converters employed and their range. In addition, the SPIW solution allows to save, in particular conditions, a significant number of optical gates compared to the SPN solution. Indeed, SPIW allows, if properly dimensioned, potential complexity and cost reduction compared to SPN, while providing similar performance.