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The authors have implemented chirped distributed feedback (DFB) grating lasers with phase shifts [λ/8, 2λ/8 and 3λ/8] distributed continuously over various axial distances, using their recently proposed method for producing bent optical waveguides. The singlemode stability of the lasers with distributed phase shifts was found to be considerably higher than for lasers with abrupt phase shifts 相似文献
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Hillmer H. Grabmaier A. Zhu H.-L. Hansmann S. Burkhard A. 《Lightwave Technology, Journal of》1995,13(9):1905-1912
We have implemented and studied a new type of tunable multiple-section semiconductor distributed feedback (DFB) laser using tailored chirped DFB gratings. Arbitrarily and continuously chirped DFB gratings are defined by bent waveguides on homogeneous grating fields with ultrahigh spatial precision. The mathematical bending functions are optimized in this case to provide enlarged wavelength tuning ranges. We present the results of model calculations, the technological device realization and experimental results of the DFB laser characterization e.g. a tuning range of 5.5 nm without wavelength gaps and high side mode suppression ratio 相似文献
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The modulation characteristics of DFB semiconductor lasers have been studied using a transfer matrix method combined with an appropriate rate equation analysis. The model takes into account longitudinal mode spatial hole burning, as well as the nonuniform current injection resulting from the axially varying Fermi voltage, and can be used for the efficient simulation of static, small-signal, and large-signal dynamic properties. The program is applied to the interpretation of experimental data from a strongly coupled InGaAsP/InP DFB laser. The experimental high-frequency properties of this device are well described by the simulations 相似文献
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Burkhard Schafer 《Datenschutz und Datensicherheit - DuD》2010,34(8):535-538
As readers of this journal will of course know, the Zugangserschwerungsgesetz has caused considerable and often very profound
debate in Germany about the limits of legal and technological interference with the freedom of access to information, culminating
in the temporary refusal of the President to sign the law into action. In the UK by contrast, a core aspect of this law, the
technical prevention of access to sites hosting illegal content by ISPs, was introduced through the so called “Cleanfeed system”
as early as 1996, with little or no public debate, and bypassing by and large all parliamentary procedure and scrutiny. This
article has a threefold aim: First, it gives a brief account of the history and implementation of the UK Cleanfeed system1;
second, it explains some of its more unusual aspects by putting them into the historical and constitutional context of policing
in the UK, and third, it highlights those experiences made with the system that are of direct relevance for the German discussion. 相似文献
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This report summarizes the 2nd International Summer School on Network and Service Management (ISSNSM’08), which was held at
the Communication Systems Group (CSG) of the Department of Informatics (IFI), University of Zurich, Switzerland, on 2–6 June
2008. Supported by the European FP6 Network of Excellence for the Management of Internet Technologies and Complex Services
(EMANICS), the ISSNSM presented within 5 days eight different topics, covering the areas of (1) security, (2) virtualization
and simulations, and (3) network monitoring and management. All of these run for a full or half day, including a short theoretical
introduction and larger practical lab course components, respectively.
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David HausheerEmail: |
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