The 5 Advantages of DWDM Technology Networks

Optical Networks offer a wide variety of features and possibilities for a stable and high-speed network. One of those features is the Dense Wavelength Division Multiplexing or DWDM technology. This technology converts data that comes from different sources together on the same optical fiber, however each optical signal is carried on its own optical wavelength. Using this technology, today, up to 32 optical wavelengths can be driven on one and only optical fiber.

The Dense Wavelength Division Multiplexing solution is made of several components:

• A Dense Wavelength Division Multiplexing terminal multiplexer. This device converts the optical signal received, converts it and re-transmits it using a 1550nm laser.
• An Intermediate Line Repeater- This device is installed approximately every 90 kilometers to compensate for the lost optical power due to the distance.
• An Intermediate Optical Terminal- this is a remote amplification site that would compensate for the optical power lost in connections that have traveled 140km or more without being amplified.
• A terminal Demultiplexer- this device separates the multiple wavelengths into an individual data.
• An optical Supervisory Channel- This is a data channel that uses additional wavelength of 1510nm to 1620nm.

This technology works in a way of separating the optical light beam into its different colors.  This method of separation has been introduced for the first time in the late 1980s when optical light at 850nm and 1300nm has been separated into the fiber using a fused coupler at one end. On the other end of the cable, another fused coupler would split the optical light into two parts and sent to two different silicon detectors. One more sensitive to 850nm and the other more sensitive to 1300nm. After that filters would remove the unwanted wavelengths.

However by the start of 1990s service providers started using Single-mode fibers and manufacturers had to find a way to separate 1300nm and 1550nm optical lights. This would show to be a hard thing to do knowing the fiber has been designed differently for 1300nm and 1550nm due to the default characteristics of optical glass. That’s why at the time 1300nm fiber links have been used for local loop links and 1550nm fibers have been optimized for long and submarine use. Later in the years the development of optical amplifiers for repeaters started giving the possibility for the WDM equipment to put 4 signals into one optical fiber.  The wavelengths in that case were around 10nm apart from each other. This WDM equipment showed not to be a problem because it have been quite easy to combine all inputs into one optical fiber. The challenge for the manufacturers has been manufacturing the demultiplexer. This demultiplexer takes the input and accumulates it into a narrow beam of light. This light is next shined on a mirror like of a device which has the function of prism which separates the light into different wavelengths by sending them off at a different angles. After that each wavelength is caught by optics and sent down a separate fibers. With this technology came the development of DWDM which relies on the same concept, however here the lasers have to be of a specific wavelength producing a stable wavelength including demultiplexers that can recognize the different wavelengths without crosstalk.

There are a couple of advantages of this technology that makes it very useful to be included in an optical network design:

• The same equipment can be used because each wavelength can be caught from the normal link. Most commonly there is no need for laser transmitters with the same wavelength of the demultiplexers. Today it’s possible to create 32 channels, however in the future the expectation is to be offered maximum 120 channels into one optical fiber.
• The use of amplifiers to act as repeaters to compensate the lost optical power. These devices can amplify the multiple wavelengths of light at the same time. They work best in the range of 1520-1560nm.
• The application of the technology- today this technology is mainly used for submarine cables. For this DWDM enhances the capacity of the cables without deploying more and more cables thus avoiding creating big, bulky and heavy cables on the sea ground. Also the positive effect of this is the cost reduction in installing new cables that will eventually lead to development of new technologies
• DWDM provides ultimate scalability and distance for fiber optic networks. Without the use of DWDM, today, most of the cloud-computing solutions would not be possible.
• It offers easy and cost-effective network expansion especially for limited fiber resource.

GBIC-SHOP Blueoptics© offer a range of Optical Transceivers that can support DWDM technology. DWDM SFP transceivers are used for bandwidth up to 3GB/s, DWDM XFP transceivers are used for bandwidth up to 11.3 GB/s, DWDM SFP+ transceivers are used for bandwidth up to 10.3 GB/s. Across all of these there is an option of choosing models with fixed DWDM settings if needed. However, a more flexible solution exists with the introduction of Tunable XFP or Tunable SFP+ transceivers which offer the possibility to set the wavelength range according to the transceiver used.