Networking

The emergence of DWDM is one of the most recent and important phenomena in the development of fiber optic transmission technology. This tutorial will introduce the fundamentals of DWDM technology, such as the components, optical amplifiers used in DWDM system, etc. Components and Operation DWDM is a core technology in an optical transport network. The essential components of DWDM can be classified by their place in the system. On the transmit side, there are lasers with precise, and stable wavelengths. On the link, there is optical fiber that exhibits low loss and transmission performance in the relevant wavelength spectra, in addition to flat-gain optical amplifiers to boost the signal on longer spans. On the receive side, there are photodetectors and demultiplexers using thin film filters or diffractive elements. Besides these components, optical add/drop multiplexers and optical cross-connect components may be used. The main job of optical fibers is to guide lightwaves with a...

Enterprise networks face a condition called fiber exhaust when the demand for backbone fiber exceeds the availability of installed fiber strands. The most obvious and expensive solution to fiber exhaust is to install more fiber. However, it’s a costly proposition. It is estimated at about $70,000 per mile, most of which is the cost of permits and construction rather than the fiber itself. There is another solution to solve fiber exhaust is to increase the bit rate of existing systems. Using TDM, data is now routinely transmitted at 2.5 Gbps and, increasingly, at 10 Gbps. Recent advances have resulted in speeds of 40 Gbps and 100 Gbps. The electronic circuitry that makes this possible, however, is complex and costly, both to purchase and to maintain. DWDM Gives the Most Cost-effective Solution for Fiber Exhaust Since two solutions mentioned above are not cost-effective enough, how to solve this problem? In fact, there is a third solution that is to...

The long distances made possible by advances in technologies such as optical amplifiers, dispersion compensators, and new fiber types, resulted in the initial deployment of DWDM technology in the long-haul networks. Once these technologies became commercially viable in the long-haul market, it was the next logical step to deploy them in the metro and, eventually, in the access networks. Besides, as we know, the networks are now being asked to carry heavy data loads, deliver streaming video and provide internet access to a rapidly growing numbers of business and private users, therefore an enormous amount of bandwidth capacity is required to satisfy the service demand by customers. As a result, DWDM metro networks emerged at the right moment. What Is a Metro Network? The overall network infrastructure can be subdivided in three domains: long-haul network, metro network and access network (see picture below). Long-haul networks are at the core of the global network. Dominated by...