28 research outputs found

    New generation of devices for all-optical communications

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    To increase the transmission capacity of future communication networks is becoming very critical. This task can only be accomplished by taking advantage of optical networks where multiplexing techniques such as Dense Wavelength Division Multiplexing (DWDM) and Optical Time Division Multiplexing (OTDM) are employed. To avoid electronic bottlenecks a whole new generation of ultrafast devices is needed. To fulfil these needs a new class of all optical devices has been proposed and developed. By taking advantage of the nonlinear dynamics in semiconductor optical amplifiers in combination with the fiber interferometers a new generation of ultrafast all-optical demultiplexers and wavelength converters has been demonstrated. Other switching technologies are also promising for the future. The latest technologies in the area of micro-machining have created very attractive low cost MEMS. Recently announced use of bubble technology for all-optical switching might also lead to the development of next generation large scale switching fabrics. This paper is an overview of the recent development in these areas

    Highly scalable optical TDM router using a computer controlled time slot selector with picosecond resolution

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    An OTDM router architecture using a highly scalable time slot tuner is discussed. Results for a 100-Gb/s, 16-channel router using a computer-controlled interface are presented. The scalability and latency of the router based upon the time slot tuner shows that aggregate bandwidths beyond 1 Tb/s are possible. We show that a maximum hardware time slot access latency of less than 3.2 ns can be achieved with this architecture enabling ultrafast optical packet routing

    TDM 100 Gb/s packet switching in an optical shuffle network

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    The feasibility of achieving large throughput in a single wavelength channel using TDM is discussed. The system is implemented with electronic routing control having networks that are often referred as transparent optical networks. The processing time required by the electronic routing controllers depends on the complexity of the routing algorithm employed, so it is critical to develop simple and efficient routing schemes. The system demonstrated packet switching in an 8-node shuffle networks using a physical node by connecting the two output links back to one of the input links using 500 m of fiber. The routing controller traces the path of a test packet by reconfiguring the node identified after performing switching on the test packet

    Demonstration of multicasting capability in a 100-Gb/s OTDM switched interconnect

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    A 100 Gb/s optical time division multiplexing interconnect based on a broadcast star architecture logically equivalent to a fully connected crossbar but uses only N switching elements is described. This single-hop, broadcast-and-select architecture offers single cycle channel access latency by employing a fast time slot tuner only in the transmitter of each node. As a router, it scales gracefully and offers 1 Tb/s aggregate bandwidth and support over 1000 nodes. The capability of the interconnect is extended to provide full multicasting functionality to a rich subset of network nodes

    Comparison of three nonlinear interferometric optical switch geometries

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    We present an experimental study of ultrafast all-optical interferometric switching devices based upon a resonant nonlinearity in a semiconductor optical amplifier (SOA). We experimentally compare three configurations: one based upon a Sagnac interferometer and the other two based upon Mach-Zehnder interferometers. By using picosecond pulses, we characterize the switching window of the three devices in terms of both temporal width and output peak-to-peak amplitude. These results are found to be in close agreement with a previously developed theoretical model. Since these nonlinear interferometric switches use an active device as the nonlinear element, relatively low control pulse energy is needed to perform switching as compared to other techniques. As a result, these optical switches are practical for all-optical demultiplexing and ultrafast optical sampling for future lightwave communication systems

    Analysis of a rapidly reconfigurable multicast capable photonic switched interconnect

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    We present a complete mathematical formalism for a rapidly reconfigurable gated timeslot tuner based on a serial feed-forward structure. This gated serial timeslot tuner has been a key component for various demonstrations including a 100 Gb/s photonic switched interconnect [K.-L. Deng, R.J. Runser, P. Toliver, I. Glesk, P.R. Prucnal, J. Lightwave Technol. 18 (2000) 1892]. Design constraints for the proper operation of the interconnect are developed. Methods to predict feasible multicast combinations and control patterns required for driving the timeslot tuner are presented in terms of a two-dimensional (2D) contour map

    Demonstration of multicasting in a 100-Gb/s OTDM switched interconnect

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    We show that a 100-Gb/s OTDM interconnect can provide full multicasting capability using a simplified node architecture. In our demonstration, subsets of 16 channels are accessed simultaneously from a multicasting node with a setup time of 3.2 ns. This additional functionality allows the interconnect to support multicasting as well as advanced services such as single-cycle multi-channel arbitration and speed-up N mode

    Microwave Method for Locating Surface Slot/Crack Tips in Metals

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    The detection of exposed (empty and filled) and dielectric covered fatigue/surface cracks on metal surfaces is an important practical issue. Recently, microwave techniques have shown the potential of detecting exposed and dielectric filled cracks and cracks covered with dielectric coatings (i.e. paint). An important issue associated with these investigations is locating the tips of a crack. This is particularly important from the repair point of view in steel bridges and other structures. In this study openended rectangular waveguide probes are used to locate the tip of empty, dielectric filled, and covered cracks. In this paper the results of extensive measurements are discussed, including the accuracy by which the tip location of a crack may be determined. The location of a crack tip can be determined using a two-dimensional crack characteristic signal (image of the crack), and more simply and accurately by using the crack tip characteristic signal. For cracks/slots used in this study, the results indicate that the tip location of exposed (empty and filled) cracks may be identified to within 0.25 mm (0.009 in.) of their actual position, while covered crack tips are located within 2 mm (0.08 in.) of their actual locations. Using optimized measurement parameters and/or a higher order mode detection scheme may result in improved tip location accuracy. Good agreement is obtained between the results of a theoretical model and the measurements, which strongly indicates the possibility of theoretically optimizing (increasing) the accuracy by which a crack tip location may be determined

    All optical code drop unit for transparent ring networks

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    In this letter, we propose and experimentally demonstrate a novel all-optical two-dimensional time-wavelength optical code-division multiple access (OCDMA) code-drop unit for transparent ring networks. The ultrafast all-optical code-drop unit is based on the terahertz optical asymmetric demultiplexer.We have demonstrated experimentally the capability to drop the correlated code at the desired node in a four-user ring network operating at 253 Gchips/s with a single-user bit rate of 2.5 Gb/s. Error-free operation is obtained. Dropping codes from multihop networks facilitates the development of optical add–drop multiplexers for OCDMA network

    Fast tunable parallel optical delay line

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    A new tunable optical delay line for OTDM applications can achieve sub-nanosecond tuning time across three time slots spaced 100ps apart. Using parallel fiber delays, the delay line requires only one modulator operating below the baseband data rate. A simple control algorithm based on a latency diagram can further reduce the average latency beyond that of the straightforward hardware implementation by 50%. Using the demonstrated delay line, 10 GHz electronics has the potential to access a throughput of 160Gb/s optical data
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