24 research outputs found

    Tunable silicon photonics directional coupler driven by a transverse temperature gradient

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    A compact directional coupler fabricated on a silicon photonic platform is presented, with a power-splitting ratio that can be tuned through a transverse temperature gradient induced by a laterally shifted integrated heater. The tuning mechanism exploits the thermally induced phase velocity mismatch between the coupled modes of the silicon waveguides. The positions of the integrated heater and the waveguide design are optimized to maximize the tuning range and to reduce electric power consumption. Asynchronous devices with an intrinsic phase mismatch are demonstrated to be more efficient, providing a tunable coupled power from 0.7 to 0.01 with 36 mW maximum power dissipation

    Compact Tunable Directional Couplers in SOI

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    A compact tunable directional coupler is realized on a silicon photonic platform. The power splitting ratio can be widely tuned through a transverse temperature gradient induced by an asymmetrically placed integrated heater

    Compact Tunable Directional Couplers in SOI

    No full text
    A compact tunable directional coupler is realized on a silicon photonic platform. The power splitting ratio can be widely tuned through a transverse temperature gradient induced by an asymmetrically placed integrated heater

    Photonic integrated filter with widely tunable bandwidth

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    We present a comprehensive design, fabrication, and characterization analysis of compact silicon-on-insulator bandpass filters with widely tunable bandwidth. The filter architecture is based on an unbalanced Mach-Zehnder interferometer loaded with a pair of ring resonators. A wide bandwidth tunability (from 10% to 90% FSR) can be achieved by controlling the resonant frequency of the rings while preserving a good filter off-band rejection. Design rules are provided that take into account fabrication tolerances as well as losses. Furthermore, the use of tunable couplers allows a more flexible shaping of the spectral response of the filter. The sensitivity with respect to nonlinear effects is carefully investigated. Operation over a wavelength spectrum of 20 nm is demonstrated, making the device suitable for channel subset selection in WDM systems, reconfigurable filters for gridless networking and adaptive filtering of signals

    Calpain-1 resident in lipid raft/caveolin-1 membrane microdomains plays a protective role in endothelial cells.

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    We are here reporting that calpain-1 is a constitutive component of a distinct lipid raft/caveolin-1 microdomain isolated from bEnd5 cells in association with endothelial nitric oxide synthase (eNOS) and heat shock protein 90 (HSP90). Perturbations in intracellular calcium concentration by Ca2+-ionophore A23187 or prolonged cell exposure to high glucose induce a significant decrease in the level of eNOS accompanied by a recruitment of additional HSP90 molecules at this site. In these conditions the cells are more resistant to cell death by Ca2+ overload. The decrease of eNOS has been due not only to its Ca2+-mediated release from the caveolin-1 aggregates but also to its digestion by calpain-1. The specific involvement of calpain-1 in digestion of eNOS is supported by the preventive effect of a synthetic calpain inhibitor (CI-2) and by the absence of calpain-2 and calpastatin in the caveolin-1 microdomain. These results suggest that the protein adjustments observed in lipid raft/caveolin-1 microdomains could be visualized as a process required to protect the cells against NO overproduction and aberrant calpain activation. Alterations in eNOS, calpain-1 and HSP90 levels have been observed in aorta of Zucker Diabetic Rats (ZDR). The loss of HSP90 occurring in these animals indicates an aberrant activation of calpain and thereby the transition from a physiological to a pathological cell condition
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