Optical networks offer a wide range of features and possibilities and are known to be stable and high-speed networks. One of the great possibilities is the Dense Wavelength Division Multiplexing (DWDM) technology. This technology combines data coming from various sources together on the same optical fiber while ensuring that each light signal does not interfere with other signals and has its own optical wavelength. Using this technology, about 40, 80, 96, and up to 160 optical wavelengths can be driven together in the same fiber.

DWDM technology consists of several components:

  • A DWDM Terminal Multiplexer: This device receives the optical signals and combines them to re-transmit using a 1550nm laser.
  • An Immediate Line Repeater: This device is implemented after appropriate distances to compensate for the loss of optical power in connections.
  • An Immediate Optical Terminal: This is a remote amplification terminal site that compensates for the lost optical power due to traveling long distances.
  • A DWDM Terminal Demultiplexer: This device receives the combined signal from one fiber and separates them into their original wavelength signals for transmitting signals to multiple sites.
  • An Optical Supervisory Channel: This is a data channel that utilizes an additional wavelength of 1510nm to 1620nm.

DWDM technology was first introduced for the first time in the late 1980s. At that time, optical light at 850nm and 1300nm was separated into the fiber using a fused coupler at one end. On the other end of the cable, another fused coupler split the optical light into two parts and sent to two different detectors, where one detector is sensitive to 850nm and the other detector is sensitive to 1300nm.

However, since 1990s, service providers started using single-mode fibers, and that’s why manufacturers had to find a way to separate 1300nm and 1550nm optical wavelengths. This at first was difficult to do because the fiber has been designed differently for both wavelengths due to the default characteristics of optical glass.

That’s why 1300nm fiber was mainly used for local loop links and 1550nm fiber has been optimized for long and submarine use. However, in the later years, the development of optical amplifiers for repeaters gave rise to the possibility of WDM equipment to put 4 signals into one optical fiber. In that case, the wavelengths were about 10nm apart from each other. This WDM equipment wasn’t a problem because it is quite easy to combine all inputs into a narrow beam of light. The main challenge was to design the demultiplexer. Now, this has been made possible.

Advantages of DWDM Technology

The same equipment can be used because each wavelength can be captured from the link. Most commonly, there is no need for laser transmitters with the same wavelength as the demultiplexers.

  • The use of amplifiers can work as repeaters to compensate for the lost optical power.
  • DWDM enhances the capacity of the fiber optic cables without deploying more cables.
  • DWDM provides ultimate scalability and distance for fiber optic networks.
  • DWDM facilitates easy and cost-effective network expansion.

If you are looking for WDM products based on Fused Biconical Taper (FBT), e.g. 980/1550nm fused WDM, contact DK Photonics.