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>> Why NRZ Isn’t Always the Best Modulation Format Most optical systems use NRZ modulation format. While NRZ modulation is suitable for long haul systems in which the dispersion of the single mode fiber is compensated for by another fiber with negative dispersion, it is not the best choice for uncompensated single mode fibers. Duobinary modulation turns out to be a much better choice in this case, since it is more resilient to dispersion and is also reasonably simple to implement. We will explain the basics of duobinary modulation and present the lab test result which shows that duobinary modulation

Jacketed optical fibers are color coded according to fiber type. Color coding enables technicians to quickly determine whether a particular cable is multimode (e.g. orange or aqua) or single mode (e.g. yellow or blue). The jacket imprint provides additional information, such as fiber size, fire code rating, and so forth. Be aware that the colors of some jacketed fiber varies from this standard. Also note that bare fibers within buffer tubes are color coded differently than jacketed fiber. The chart below pertains only to jacketed fiber. Fiber Optic Color Codes by Fiber Type FIBER COLOR CODE Non-Millitary Applications Millitary Applications

Ciena Corp. says the Japan-US Cable consortium is upgrading its trans-Pacific submarine network, which spans nearly 23,000 km between the US and Japan, with Ciena’s Wavelogic 3 coherent 100G technology. Expected to be in service in early 2013, the upgraded network will bring 5 Tbps of additional capacity to a crucial global network route connecting North America and northern Asia. As the first direct coast-to-coast 100G trans-Pacific submarine network, this will allow Japan-U.S. Cable customers to enjoy the benefits of increased bandwidth and support rapidly increasing capacity demands. The Japan-US Cable is made up of more than 26 consortium members,

All amplifiers degrade the signal-to-noise ratio (SNR) of the amplified signal because of spontaneous emission that adds to the signal during its amplification. The SNR degradation is quantified through a parameter Fn, called the amplifier-noise figure in analogy with the electronic amplifiers, and is defined as (Equation 1.12) where SNR refers to the electrical power generated when the signal is converted to electrical current by using a photodetector. In general, Fn would depend on several detector parameters which govern the shot noise and thermal noise associated with the detector. One can obtain a simple expression for Fn by considering an

Fujitsu says it has collaborated with NTT Communications Corp. on a successful field test of coherent 100-Gbps DWDM transmission via a commercial fiber-optic cable between Tokyo and Osaka. The test clears the way for full network construction using the 100-Gbps DWDM systems. While Fujitsu has implemented coherent 100-Gbps DWDM systems outside of Japan, the field test opens the door for its first deployment in Japan. The test was conducted using dispersion-shifted fiber in the L-Band, which is often used in Japan for long-haul transmissions. The field test simulated real-world situations, such as fiber-optic cable changes in accordance with transmission-circuit route