Performance Control and Analysis of Optical Fiber Instrumentation System in LAN Environment

Abstract

Optical fiber refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic wire or fiber. Optical fiber carries much more information than conventional copper wire. Optical fiber has been proven to have the widest bandwidth compared to any other media known, including wireless, copper wire, sonar, and even free-space-optics. Tera hertz bit rate has been demonstrated in the lab by using the standard single-mode telecom fiber. As a comparison, the entire useful radio bandwidth worldwide is only 25Gbps, a mere 0.1 percent of the bandwidth supported by a single strand of fiber. As a result, optical fiber can easily replace a large bundle of copper wires while significantly boosting system bandwidth. In optical fiber technology, single-mode fiber is an optical fiber that is designed for the transmission of a single ray or mode of light as a carrier and is used for long distance signal transmission. For short distances, multi-mode fiber is used. Single mode fiber has a much smaller core than multimode fiber. A LAN is a communication network that provides interconnection of a variety of devices such as computers, terminals, and peripheral devices within a limited geographical area. LANs typically provide communication facilities within a building or a campus and only span several kilometers. LANs usually use much higher data rates (typically more than 1 MBPS). LANs generally experience fewer data transmission errors than long haul networks. Many LANs simply broadcast messages and thus do not require message routing algorithms. Even without a broadcast facility, the routing algorithms are much simpler. A LAN is typically owned by a single organization because of its limited geographical coverage. This leads to lower administrative, maintenance complexities and costs. The most common filter responses are the Butterworth, Chebyshev, and Bessel types. Many other types are available, but 90% of all applications can be solved with one of these three. Butterworth ensures a flat response in the pass-band and an adequate rate of roll-off. A good "all rounder," the Butterworth filter is simple to understand and suitable for applications such as audio processing. The Chebyshev gives a much steeper roll-off, but pass-band ripple makes it unsuitable for audio systems. It is superior for applications xiv in which the pass-band includes only one frequency of interest (e.g., the derivation of a sine wave from a square wave, by filtering out the harmonics). In this thesis, entitled “Performance Control and Analysis of Optical Fiber Instrumentation System in LAN Environment” presents analyses for different combinations of modulation formats, fiber lengths and filters using eye diagrams and optical spectrums for single-mode and multi-mode fiber in LAN environment. Simulation is done using OPTSIM to measure OSNR, Jitter, BER, Q-factor and eye opening for each combination. OPTSIM is an intuitive modeling and simulation environment supporting the design and the performance evaluation of the transmission level of optical communication systems. When there is no limit of bandwidth then single-mode fiber gives the better results with RZ modulation format in LAN environment. Multi-mode fiber is better for limited bandwidth with RZ modulation format in LAN environment. The RZ modulation format gives the better result as compare to NRZ modulation format. Length of the optical fiber should be small. The Butterworth filter gives the best results among these three filters. The best combination for data transfer in the LAN environment is single-mode fiber with RZ modulation format, 50 meters length of fiber and Butterworth filter at the receiving end.