Of course, this is unilluminated fiber or, in other words, a communications medium (fiber) without equipment at the ends that illuminates or sends a laser signal with data through said medium.
In the world of communications, we know that operators are responsible for establishing the path or "means" of transport to link the different nodes and to establish communications between them.
When this means of communication is copper, telephone lines are its final application and thus establish voice circuits and ADSL links, so well known today for their use in Internet access.
There are also RF or radio frequency links that similarly send RF signals to carry information between nodes. Wi-Fi links, so commonly used, are well-known examples, allowing several computers to be connected in a "multipoint" topology.
The world of fiber optics has undergone a tremendous evolution in a very short time with concepts that are difficult to assimilate except within the professional environment, so the term "dark fiber" doesn't tell us much at first.
Currently, there are highly developed fiber optic networks, fiber that forms an extensive communications layer within our cities, as well as interconnection between them, enabling large transport infrastructures that provide today's communications.
The operators that act as such have and use these dense networks, sending information between the different interconnection nodes. This transmission is carried out using digital laser light signals through the optical fiber, encoding the information in zeros and ones, or by switching a laser on and off at one end so that the information is received by a photoreceptor at the opposite end.
This equipment at the ends is provided by the operator offering its services to the user, supplying circuits of varying speeds.
The evolution of these services means that sometimes fiber optic operators have another operator as their customer, which in turn offers managed communications services. In these cases, the first operator is referred to as the "dark fiber operator," since the equipment that activates the fiber is the responsibility of the second operator.
We've seen something similar in the past with copper operators. Initially, the operator's standard service was a line along with a leased telephone (or modem), and they didn't directly connect the copper line to the user's equipment. Later, with the evolution of this service, users switched to directly contracting the copper line and receiving a connection socket without a telephone line, which they were responsible for purchasing. By analogy, we could refer to this as an "unlit copper line.".
Currently, fiber to the home (FTTH) offers fiber optic connections that terminate at the user's home in a device called an ONT, which is supplied by the operator. However, in the coming years, this service will evolve similarly to dark fiber, utilizing the equipment the customer already owns.
Traditionally, laser signal transmission over fiber was achieved using a laser that sent a signal encoded in zeros and ones (off, on) at a specific wavelength or frequency of light. The data transmission capacity with this system typically reaches 10 Gbps.
Systems currently exist that can transmit "n" signals through a single fiber using the same traditional laser switching mechanisms. This is known as wavelength multiplexing over fiber, or the transmission of multiple colors or frequencies through fiber. In Spain, transmission systems are manufactured by introducing "n" lasers of different "colors" or wavelengths (or frequencies) into the fiber, thus multiplying the capacity of this medium in such a simple way, increasing the total capacity of the fiber link, for example, to n x 10 Gbps.
There are very few leading companies in the world that can transmit 240 wavelengths or lambdas over fiber. Fibernet in Spain is one of them, offering capacities of 2.4 Terabits/sec per fiber link.
To give you an idea of what this transmission capacity means, a single link could connect the entire population of Spain from one end to the other via telephone if a traditional fiber optic telephone system were integrated into Fibernet's transmission solution.
But the evolution of the term "dark fiber" continues, and a new concept has emerged: "dark lambda," which is used to determine the capacity of fiber optic networks in mesh topology and allows for the routing of lambdas through the "optical lanes" of fiber optic highways. Operators will offer connectivity with varying bandwidths by using one or more lambdas between the different nodes of a mesh network.
With the new backbone network capacities of 100Gbps, 400Gbps, and even 1000Gbps per service, we can envision vast access capabilities with new services that, initially, could be provided by carriers of carriers and ultimately to the end user. This would enable transport capacities unimaginable today. Consider, for example, a similar FTTH service that provides the end user with a 30Gbps FTTH connection, or in other words, three 10Gbps lambdas.
Although a technical feasibility for an extensive fiber optic mesh with multiple intersection points at an ultra-national level that allows the routing of lambdas between its nodes as if they were IP packets is foreseeable, only when the on-demand route of that large bandwidth is dynamically established will we be able to talk about services that require this technology, and which we do not yet know.
The reality is out there on the streets. A vast mesh network of fiber optic cables reaches our homes, runs through our streets, and will continue to expand in the coming years as the demand for content grows and our internet access capacity is exceeded. Then we will be able to see fiber optic networks as the networks of the future.
Author:
José M. Marín, President of Fibernet
