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Over the last decade, fiber-optic cables have been installed by carriers and have become the backbone of their interoffice networks. Thus, fiber-optic cables have become the mainstay of the telecommunications infrastructure. Using time division multiplexing technology (TDM), carriers now routinely transmit information at 2.4 GBps on a single fiber, and with the use of deploying equipment, they may quadruple that rate to 10 GBps. High bandwidth applications and the explosive growth of the Internet, however, have created capacity demands that exceed traditional TDM limits. As a result, the once seemingly inexhaustible bandwidth promised by the deployment of optical fiber in the 1980s is being exhausted. To meet growing demands for bandwidth, a technology called Dense Wavelength Division Multiplexing (DWDM) has been developed that multiplies the capacity of a single fiber. DWDM systems being deployed today can increase a single fibers capacity 16 fold, to a throughput of 40 GBps!

Dense wavelength division multiplexing (DWDM) is a technology that puts data from different sources together on an optical fiber, with each signal carried on its own separate light wavelength. Using DWDM, up to 80 (and theoretically more) separate wavelengths or channel of data can be multiplexing into a lightstream transmitted on a single optical fiber. In a system with each channel carrying 2.5 Gbps (billion bits per second), up to 200 billion bits can be delivered a second by the optical fiber. DWDM is also sometimes called wave division multiplexing (WDM).

Because each channel is demultiplexed at the end of the transmission back into the original source, different data formats being transmitted at different data rates can be transmitted together. Specifically, Internet (IP) data, Synchronous Optical Network data, and asynchronous transfer mode data can all be travelling at the same time within the optical fiber.

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Telecommunications Development, Asia-Pacific

The fundamental elements of a fibre-optic system traditionally have been the source (laser or light-emitting diode), the optical fibre over which the signal is transmitted, and the receiver, which decodes the pulse back into an electronic domain.

In the past, if a carrier needed to increase the number of messages sent along an optical fibre, the response would be to increase the number of pulses flowing through the fibre by developing a faster source and receiver, a process known as time division multiplexing (TDM). As synchronous communications replaced asynchronous transport along a fibre-optic cable, faster TDM has translated into higher rates of the synchronous digital hierarchy (SDH) or of synchronous optical network (SONET). SDH rates grew from STM-4 to STM-16 optical networks (SONET expanded from OC-12 to OC-48). Some vendors have even begun delivering SDH-64 (OC-192) systems, which can deliver up to 10 Gbps.

For more of this article, visit Telecommunications Development.

This article goes on to explain Dense Wavelength Division Multiplexing and some important issues in its development.

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Optical Networking and Dense Wavelength Division Multiplexing (DWDM)

Muralikrishna Gandluru, Ohio State University

This paper deals with the twin concepts of optical networking and dense wavelength division multiplexing. It also talks about the various optical network architectures and the various components of an all-optical network like Optical Amplifiers, Optical Add/Drop Multiplexors, Optical Splitters, and so on. Important optical networking concepts like wavelength routing and wavelength conversion are explained in detail. Finally this paper deals with industry related issues like the gap between research and the industry, current and projected market for optical networking and DWDM equipment and future direction of research in this field.

I found this page to have alot of information about Dense Wavelength Division Multiplexing (DWDM) as well as Optical Networking. Listed below are the links that will help you navigate this page:

1.2 Dense Wavelength Division Multiplexing

2. DWDM SYSTEM

2.1 Optical Transmission Principles

2.2 Network Classification
2.3 Optical Amplifiers
2.4 Synchronization
2.5 Security

3. DWDM COMPONENTS

4. OPTICAL NETWORK ARCHITECTURE

4.1 Virtual Topology

4.2 Optical Layer and Higher Layer Interface

5. DWDM ARCHITECTURE

5.1 ATM over DWDM

5.2 IP over DWDM

6. WAVELENGTH ROUTING IN OPTICAL NETWORKS

6.1 Efficient Routing Algorithms

7. WAVELENGTH CONVERSION IN OPTICAL NETWORKS

7.1 Wavelength Conversion related Algorithms

8. MARKET SCOPE AND COMPANY PROFILE

8.1 Ciena Corporation

8.2 Lucent Corporation
8.3 Sycamore Networks
8.4 Ericsson's ERION

SUMMARY

REFERENCES

LIST OF ACRONYMS