WDM's for FTTH
In a world that changes at the speed of light, we are all in the quest for greater bandwidth. As more people utilize the internet in their everyday lives for work, research, e-mail, and entertainment, the need for bandwidth increases. As cable TV and telephone increase their capabilities and features they also require more bandwidth and higher speeds.
One of the solutions to the need for greater bandwidth can be accomplished by wave division multiplexing (WDM). Multiplexing is done by combining different wavelengths over one optical fiber. In most fiber applications signals are sent down a fiber at one particular wavelength, such as 1310nm or 1550nm. Each wavelength is capable of carrying a certain amount of information.
When you multiplex, you can combine many wavelengths over the same fiber simultaneously. Wavelengths can be described as "colors" of light. Blue light is in the range of around 400nm and red light is about 600nm. Light sources in fiber are usually 850nm and higher, which are infrared lights. WDM's are typically used in single mode fiber systems due to the large bandwidth requirements.
What happens when you use a WDM, which looks like a splitter, is that you inject light from multiple sources with different wavelengths into each leg. They then travel over the fiber and are de-multiplexed at the receiver end. This technique enables the user to multiply the capacity of the fiber by however many wavelengths they are using. For example, if 1550nm can support 40,000 telephone conversations, then by using a 1 x 16 switch multiplexer, that same fiber can now support 640,000 conversations.
One of the greatest needs for greater bandwidth can be seen in the "Fiber to the Home" (FTTH) project. FTTH is where fiber will be brought directly to the side of your home to support your cable TV, telephone service and internet needs. It looks much like the utility box that you currently have on the side of your home, only with fiber jumpers inside. Currently Optical Solutions is the leader in the FTTH project.
Using the "Fiber Path" system one fiber can support 32 homes with CATV, telephone and Internet service. Resident subscribers can receive up to 6 telephone lines, 80 CATV channels plus digital CATV, and 10 Mbps high speed data transmission.
Although FTTH is still very new, the need for it is growing at a rapid rate. How would you like to use video on demand where you can select from thousands of movie titles, and if you choose to own it, just click on an icon to buy it? Or how about watching the world series, missing a home run and just rewind, or pause. You will also be able to purchase MLB merchandise by clicking the MLB store icon on your TV. These are just some of the features of future of FTTH.
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