Over the years, mankind's understanding of optics has grown - we have mastered the measurement of light, learned how it is produced and how it travels, and as a result built up our understanding of the universe. Fifty years ago, Corning mastered the use of fibre optics, a revolutionary new material, to efficiently transmit light signals over long distances.
Today, the latest and most influential innovations in the field of optics allow us to exploit the spectrum of different wavelengths (created by the breakdown of light). This promising technology, known as Wavelength Division Multiplexing (WDM), can help network operators stay ahead of the curve in meeting the growing demand for bandwidth.
Imagine light passing through a prism. Through dispersion, light is broken up into various colours and we see a 'little rainbow'. Each colour represents a set of wavelengths, a 'band', and we can separate out different wavelengths of light and operate them independently of other colours. In telecommunications, we use fibre optic cables to transmit information, usually in the form of red or green lasers. In this process we use all the wavelengths within the 'red' or 'green' part of the spectrum, rather than isolating individual wavelengths. Using WDM, we can break up the laser into different wavelengths of light, meaning that the same information that used to occupy the entire 'colour' band in transmission now occupies only a small part of the band. This is why WDM is so promising in terms of increasing network capacity.
We deploy WDM in our networks using "multiplexers" (mux) and "demultiplexers" (demux). Essentially, these products are the equivalent of lenses attached to active devices (lasers), allowing us to manipulate the individual wavelengths within the laser for transmission in the fibre. The transmission of an optical signal (which might represent a phone call, a text message or a video) is then sent through the laser and guided to a specific wavelength by a multiplexer. These signals travel along the fibre together with other transmitted signals of different wavelengths. The multiplexer then receives and processes these transmitted signals, separating the individual signals into a form that can be understood by the transceiver responsible for receiving the information.
Predictably: as light continues to be broken up into more and more wavelengths, the potential capacity of a single optical fibre grows dramatically.
It is important to note that the technology behind WDM is evolving rapidly and we have not yet reached the limit of how many different wavelengths can be transmitted in a single fibre. Coarse Wavelength Division Multiplexing (CWDM) technology is the first generation of WDM technology and can provide up to 18 channels. Dense Wavelength Division Multiplexing (DWDM) is a new iteration of the technology that can provide up to 160 channels. One of the major problems facing today's connected world is the depletion of fibre resources, where the demand for fibre exceeds the amount of fibre available in the network. By using less fibre to transmit and receive multiple services, the development of WDM technology can alleviate the problem of fibre depletion.
As the demand for bandwidth continues to grow, operators are looking at all feasible ways to accelerate the deployment of capacity in their networks - whether it be data centres, urban cellular networks, or even long distance networks connecting cities, to name a few. The core value of WDM technology is that it allows operators to increase capacity without having to lay additional cables. This is particularly important in congested areas where it is difficult to find space to run additional cables. Given the bandwidth demands operators are currently facing, WDM technology is increasingly being deployed across the globe.
Network deployments are often divided into two categories: greenfield and brownfield deployments. Greenfield deployments refer to new construction - deploying networks on 'green', undeveloped land. Brownfield deployments are usually found in already developed spaces where people have to work with (or around) existing infrastructure. In a greenfield environment, one can easily add additional fibre to the planning process. In a brownfield environment, however, one needs to take into account the existing space constraints and it is not always possible to add additional fibre. Given this, it is extremely challenging to meet the bandwidth requirements of 5G, IoT and smart communities, for example. In this environment, WDM technology is a key component in enabling interconnectivity in the future.
The pace of innovation in WDM technology means that new advances are constantly being made in terms of technology advancement as well as implementation. Staying abreast of the features and best practices associated with WDM products will be the order of the day.
