While there may be an extensive optical fibre infrastructure currently in place, not all of it is in use. When we talk about dark fibre, we are talking about the portion of that infrastructure that is as yet unused. So, why is it called dark fibre?

Optical fibre carries and conveys information using pulses of light -- so it makes sense that optical fibre cables that are not being used to convey information are described as 'dark'.

It also makes sense that a use should be found for this unused cabling. Which is why dark fibre networks are leased out to companies and individuals by dark fibre providers for personal and business use. Leasing a dark fibre network can have a number of advantages -- of which, we will discuss a little bit later.

A little bit of history

One reason dark fibre exists is the cost of creating an optical fibre network -- where the cost of creating the network is much higher than the cost of the cables themselves. The true cost of creating a network comes with the planning and routing, the procurement of permissions, the creation of ducts and channels for the cables, and finally the installation and connection.

When creating an optical fibre network, many planners choose to install much more cabling than is currently required. So, if their optical fibre requirements grow, the infrastructure is already in place, and there is no need to spend more money expanding the network. The extra cabling also works as a failsafe -- so if the cabling in use fails, there is still unused cabling available to take up the slack.

Another reason for dark fibre's existence is the dotcom bubble. During that time, telecoms traffic -- especially data traffic -- was predicted to grow exponentially for the foreseeable future. Many telephone companies built an excess of optical fibre networks in order to corner that predicted market. When the bubble burst, a large portion of that new fibre network that went dark.

Add to that the availability of wavelength-division multiplexing -- where the capacity that could be placed on a single fibre increased -- the amount of fibre required decreased even further.

Why choose dark fibre?

• Dark fibre can provide a point-to-point connectivity solution that offers a secure way to deliver high-speed data applications.
• It can be scalable, allowing it to grow with your organisation. It allows you to create your own network without the need to invest in your own fibre-optic infrastructure.
• Dark Fibre offers extensive coverage, so you can expand your network as and when you need it.
• It gives you full control, so you can choose how, when and what equipment to use.
• It is private and secure. You receive allocated fibre dedicated to your business, providing you with physical separation from any other service.