With the fast development of the optical network, the demand for wider bandwidth and faster data transmission rates over farther distances are increasing day by day, which makes more and more fiber cables need to be installed when the optical network is designed. However, once the available fiber infrastructure is exhausted and can’t meet the increasing communication need any more, laying more fibers would become an impracticable or uneconomical method. Thereby, new capacity for the network needs to be created. In order to solve this, experts try to fall back on two new methods to expand the capacity of our network: increasing system bitrate to multiplex more signals and using WDM (wavelength division multiplexing) technology.
It is well known that both increasing system bitrate to multiplex more signals and using WDM technology can expand the capacity of our network. But the fact is that WDM technology is more commonly used for expanding the capacity of our network. What makes WDM technology so popular in optical network? What’s the advantage of WDM technology? The following will introduce the two methods of expanding the capacity of our network and seek the differences of the two methods.
Increasing System Bitrate
Nowadays, most of our systems have already worked in 2.5 GB network. If we want to increase our system bitrate to multiplex more signals for expanding capacity, we should upgrade our system to 10 GB network. However, the upgrading process requires changing out all the electronics in our network which should be an expensive project. Taking the high upgrade cost into consideration, it is not recommended to expand capacity by increasing system bitrate to multiplex more signals.
Using WDM Technology
In contrast to upgrading our system, using WDM technology to expand the capacity of our network should be a quite advisable, cost-effective way that doesn’t require more fiber cables or changing out the electronics in our network. WDM technology takes great advantage of the enormous bandwidth of the optical fiber and makes bidirectional communications via one strand of fiber possible. To be brief, WDM technology creates virtual fibers to transmit data, which is the optimal method to expand capacity in optic network at present. As WDM technology is developed fast and tended to be mature, it is strongly advised to use this technology for promoting the network with high-volume data transmission over one single optical fiber.
The word of WDM stands for wavelength-division multiplexing. From its name, it is easy to know that the technology is using different wavelengths of light from a laser or a LED to multiplex two or more optical carrier signals over a single optical fiber. In its working process, without using additional fibers, optical carrier signals with different wavelengths are combined at the ingress, then transmitted together through the single optical fiber, and finally separated into individual signals with differing wavelengths at the express again as shown in the following figure.
At present, there are two types of WDM technology, CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing), both of which are indispensable and popular technologies to expand capacity on the fiber links. To some extent, WDM technology strongly multiplies the capacity of the network that plays an important role in meeting the increasing requirement of modern network.
The WDM revolution has already occurred with unexpected swiftness, which is more popular and commonly used for expanding the capacity than increasing system bitrate in today’s network. Although WDM technology is lack of a long history, the maturity of the technology have been realized WDM systems tailored specifically to the metropolitan area, providing high bandwidth and high capacity at a relatively low cost.