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A new method for reliability assurance of long length optical glass fibers is presented. This method is based on a simple equation by fracture-mechanics theory and provides failure probability prediction for fibers after proof testing. The prediction is made by using dynamic fatigue data obtained by simple tensile tests and failure number during proof testing. The experimental results are found to be in good agreement with those predicted by the theory, and it is verified that the method is useful to make reliability assurance of long optical fibers for long- term use.

Coated single-mode fibers with various coating thicknesses were manufactured, and loss increases due to cooling were measured. It was found that the excess loss increases steeply in the small V-value region at low temperatures. A simple model for fiber bends in the coating was introduced, and the increases in loss were related to the strain resulting from use of the model. It would appear that the axial compressive strain has a serious influence on the loss increases. A suitable silicone buffer layer for preventing loss increases has been determined. The selected silicone layer diameter is 0.45 mm for a 0.9-mm nylon outer layer diam.

A web-based design and control system has been published [5] how lightpaths are assigned to pairs of nodes investigated for regional optical IP (Internet Protocol) as well as the required wavelength number. networks. The system can design lightpaths connecting Another design issue is the reconfigurability of the nodes such that given traffic is groomed with minimum lightpaths in WDM networks to groom traffic effectively number of wavelengths, or give a reserve design with and for connection provisioning [6]. The lightpath can be additional lightpaths to groom future traffic. reconfigured dynamically or statically, depending on the Reconfigurable optical add/drop multiplexers (R-OADMs) wavelength-routing device. For the reconfigurable were also investigated and manufactured. An experimental purpose, wavelength mux/demux devices with the network with the R-OADMs was constructed, and the ' S .~reconfigurable function were proposed: optical add/drop control function of the implemented system was examined multiplexers (OADM) with optical switches [4] or with by reconfiguring the lightpaths in the experimental network. waenghtabedvcs7]The R-OADMs could be controlled and the lightpaths could waelnength-tunab devices [7]. be reconfigured successfully by the system.The networks for regional access applications can be classified as ring and star topologies [8]. Now the double star topology with optical power splitters is used widely I. INTRODUCTION for FTTH (Fiber-To-The-Home) applications, and the ring Recently, optical networks have been introduced topology is dominant [1]-[6], [8] for the MAN and WAN commonly to satisfy the rapid increase of traffic demands.applications. In such M\AN and WAN applications, lots of In addition to the high capacity characteristics of optical business data are transmitted as well as voice data for fibers, WDM (Wavelength-Division Multiplexing) telephone service. To transmit such business data, cell technologies provide more bandwidth per fiber, and are relay and frame relay services are used in public networks. used in core backbone networks, metropolitan area Recently more IP and Ethernet transmissions are used, networks (MANs), and regional area networks. In the because many services are integrated and provided over IP, MANs and regional networks, wavelength routing including business data storage/processing by web servers capability in WDM networks is also investigated as well and VoIP (Voice-over-IP). Moreover, all communication as the effective use of the high capacity. In the wide area services are going to shift to IP networks as the next networks (WANs) and MANs to connect buildings and generation network. offices for business use, the wavelength routing capability Another approach is the dark-fiber or customer-owned should be used more effectively than others. networks [9]. This new type of network is becomingThe design procedures for the wavelength-routed increasingly common among large enterprise networks, networks have been investigated and published. The university research n...

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