262,370 research outputs found
100 Gigabit Internet why and how : the technology behind it
Get PDFThe need to keep transmission capacity growing is a never ending process which is becoming more and more challenging to fulfill. Over the years we have witnessed data rates to grow from less than one bit per second all the way up to tens of Giga bits per second thus leading to the overall aggregate throughputs of several Terra bits per second which can be observed in today's the most advanced optical communications networks. This progression was accomplished by replacing earlier simple copper conductor wires by a twisted pair, then by coaxial cables which later on were superseded by microwave transmission systems. After fundamental discoveries leading to coherent light sources - lasers and fiber optic cables, fiber optics data communication became the prevailing way in data transmission. The combination of fiber optics, optical data multiplexing techniques, and advanced electronic signal processing helped to realize data transmission capabilities which just a few years ago would have been very hardly even to imagine
Improving multi access interference suppression in optical CDMA by using all-optical signal processing
No full textThis paper presents the study of a novel alloptical method for processing optical CDMA signals towards improving suppression of multi access interference. The main focus is on incoherent OCDMA systems using multiwavelength 2D-WH/TS codes generated using FBG based encoders and decoders. The MAI suppression capabilities based on its ability to eliminate selective wavelength pulse processing have been shown. A novel transmitter architecture that achieves up to 3dB power saving was also presented. As a result of hardware savings, processing cost will be significantly reduced and power budget improvement resulted in improved performance
Statistics of attenuation due to rain affecting hybrid FSO/RF link : application for 5G networks
No full textThis paper shows that FSO could be an option for backhauling among microcells in future 5G systems in areas where fog is not a concern as very short LOS links (few hundred meters) would be required. In this respect, monthly CCDFs of rain attenuation at both RF (28 GHz) and optical bandwidth have been calculated in the area of Hyderabad (Pakistan). FSO links with simple OOK modulation would be able to reach targeted data rate of hundreds of Gbps for 99.99% of time provided the link length is less than few hundreds of meter
Analysis of a rapidly reconfigurable multicast capable photonic switched interconnect
No full textWe 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
In situ method for power re-equalization of wavelength pulses inside of OCDMA codes
Get PDFA simple in-situ method to equalize power among individual wavelengths pulses representing two-dimensional wavelength-hopping time-spreading OCDMA code originally generated by a fibre Bragg grating-based OCDMA encoder is presented. Experimental data obtained in a field-based multiuser OCDMA testbed shows that applying this method results in system performance enhancements which was demonstrated by observing improved bit error rate (BER) during the field trials
Measurement of Optical Pulsewidth in the Picosecond Regime Using a Non-linear Fiber and Power Meter
No full textA technique for the characterization of picosecond pulse widths is presented, based a non-linear optical fiber loop mirror and power meter measurement. Pulse-widths in the 2-10ps range are successfully recovered with a resolution of 0.25ps
Ultrafast all-optically controlled 2×2 crossbar switch
No full textAll-optical packet switching using all-optical routing control, where both ultrafast address recognition and routing of photonic packets were all optically performed on a header with 4 picosecond bit period, was demonstrated. Packets were self-routed through a node with no need for optoelectronic conversion. Terahertz optical asymmetric demultiplexer (TOAD) was used as an optically controlled 2×2 routing switch and as an all optical routing controller. TOAD read the individual address bits in the tightly compressed packet header and set the state of the routing switch. The bit-error rate at the switching element was measured to be less than 10-9
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
New generation of devices for all-optical communications
No full textTo 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 OTDM router using computer controlled time slot tuner with picosecond resolution
No full textAn optical time division multiplexing (OTDM) router, using a highly scalable time slot tuner, is discussed. Channel access in OTDM networks is achieved by using time slot tuners and all-optical demultiplexers. Timing precision of <1 ps is required to tune, multiplex, and demultiplex individual channels within the OTDM frame. An error-free 100 Gbit/s broadcast star architecture that can be used as the backplane for this router is presented. The router scalability based on the time slot tuner is analyzed and shows that the architecture can offer 1 Tbit/s aggregate bandwidth and support over 1000 nodes. This represents an order of magnitude improvement over current state-of-the-art electronic routers
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