Wave Division Multiplexing

   (WDM) A form of frequency division multiplexing specifically for packing many Optical Carrier n signals into a single optical fibre.

The technique relies on the fact that a laser can be designed to emit monochromatic light. Each signal to be transmitted is attached to a laser that emits a different colour light beam, all the light beams are sent at the same time and a receiving device splits the colours into the original signals again. The device that joins the signals together is known as a multiplexor, and the one that splits them apart is a demultiplexor. With the right type of fibre you can have a device that does both and that ought to be called a mudem but isn't.

The first WDM systems combined two signals and appeared around 1985. Modern systems can handle up to 128 signals and can expand a basic 9.6G bps fibre system to a capacity of over 1000G bps. These systems are sometimes called dense wave division multiplexing or DWDM systems.

DWDM systems are popular with telecommunications companies because they allow them to expand the capacity of their fibre networks without digging up the road again. All they have to do is to upgrade the DWDM cards at each end. However DWDM systems are expensive and complicated to run. There is currently no standard for DWDM kit which makes it awkward to integrate with older but more standard SONET systems.  

According to industry pundits, the forecasted growth of the dense wavelength division multiplexing (DWDM) market will leap from US$800 million last year to US$7.1 billion in four years' time.

Optical networking refers to the communications between computers, telephones and other electronic devices using light. Read on for an insight into the trends, market drivers, and technology behind this high bandwidth conduit.

TUTORIALS
Tutorial: Optical Networking
An optical network is far more reliable and offers many advantages over electricity and copper wire. Industry experts predicted that the growth of the dense wavelength division multiplexing (DWDM) market will leap from US$800 million in 2000 to US$7.1 billion in four years' time.

Fundamentals of Optical Networking
Telephony providers began deploying optical fibre for long distance voice trunks as early as 1977. Today's fibre optic systems support throughputs as high as 1Tbps, with unassisted propagation distances of 3000 miles and farther. Read about how optical fibre systems work since it was first used in 1977.

Wave Division Multiplexing (WDM)
The amount of traffic-data, voice, and multimedia-travelling over the Internet and other networks grows at rates that are hard to quantify, but everyone agrees the increase is beyond anyone's wildest dreams. Cabling providers rely on technologies that increase the amount of data a single piece of fibre can handle -- Wave Division Multiplexing.

TREND
Vendors focus on optical networking
Optical networking players are gearing up for the increasing demand for bandwidth in the Asia-Pacific region. Most of the cabling and networking companies have come to a conclusion that North Asian countries such as China, Korea and Japan, will be the biggest optical markets in Asia.

STANDARDS
Six Optic Network Trends
Now, the current industry buzzword is "intelligent optical networking"-as manufacturers tend to the needs of operators requiring better-designed network management and provisioning. As the market grows, we expect industry shifts on the horizon that just might alter the way we'll view the optical networking space in coming years.

WHAT'S NEW
The Optical Revolution
New optical gear due out in year 2000 will fundamentally change the business of designing and delivering telecom services. What kind of rewards can network managers look forward to?

TEST & MEASUREMENT
Let There Be Light
Growing customer demand for bandwidth is forcing operators to make some demands of their own-on their fibre networks. As service providers try to stuff more and more channels into a given radio frequency transmission window, it's important to make sure that the performance of the optical components measure up to the task.

ARCHITECTURES
Go Optical
The future network is optical. That's not in question. What is being asked is what shape that network will take and when are we likely to see the all-optical intelligent network. Are service providers moving to put IP directly over dense wave division multiplexing (DWDM); or will we continue to see a synchronous digital hierarchy (SDH) layer or a synchronous optical network (SONET) layer in the network?