The worldwide communication network has a physical form. Beneath urban streets and across ocean floors, cables carry huge volumes of information that provide the connectivity on which modern life thrives. Fibre optic technology is at the heart of this network, supporting everything from industrial automation to broadcast media. As the demand for data increases, so too does the need for fibre solutions that can handle tough conditions without compromising performance.
Understanding Optical Communications
Optical fibre has been a popular solution for several decades. As the internet grew in popularity, the capabilities of the traditional copper-based communication network became a limitation. As the demand for greater bandwidth grew, fibre became an ideal choice for high-speed, long-distance communication.
Conventional electronics use an electrical current passing through conductive wires, usually made from copper. Signals are transmitted along the wire, but the resistance of the conductor limits how far they can travel. In contrast, optical communications transmit data using light passing through a fibre made of glass. The glass itself is extremely pure to minimise the loss of signal over long distances, and is drawn out into tiny filaments. An optical fibre is made of two layers of glass, each with a different refractive index.
Light travels along the core of the fibre by total internal reflection. You can see this effect in action. When looking straight into a large body of water, light can travel freely between the interface between the water and the air. However, when viewed at a shallow angle, the light from the sky is reflected back to the viewer, and the water appears opaque. This is the principle at work within an optical fibre. The interface between the two layers, known as the core and the cladding, keeps light inside the core like a rubber ball bouncing along a steel pipe.
The size of the core governs the volume of data that can be transmitted along a fibre. In contrast to electrical systems, in which a larger conductor provides a lower resistance, the smallest cores offer the largest capacity. The core of a multimode fibre has a larger diameter, typically 50 or 62.5 microns. This allows light to travel along more than one path or mode, meaning that a signal may take several different paths to reach its destination. To compensate, it is necessary to delay transmission of the following signal so that there is no risk of it interfering with the previous signal that has taken the slowest path.
The core of a single mode fibre is much smaller, typically with a diameter of only 9 microns. This narrow core allows the light to travel along a single path, so more data can be transmitted without one signal interfering with another.
The Challenges of Fibre
One of the greatest challenges of optical communications comes when two fibres must be joined. Unlike an electrical circuit that simply requires two conductors to touch for current to pass from one to another, optical fibres require great precision to ensure they are aligned. If the cores are misaligned, there is a risk of losing some of the signal at the join. To provide the best possible connection, fibres are fitted into ceramic ferrules to keep them stable and ensure good physical contact. Even the slightest misalignment or the smallest speck of contamination between the two surfaces will significantly affect the optical signal.
The face of an optical connector therefore needs to be prepared carefully and kept clean during use. This is simpler for applications that do not have to contend with harsh environments. In data centres and telecommunications, terminations can be protected and are unlikely to be disconnected frequently.
However, when used in the field, the requirement to protect the vulnerable mating face of the connector becomes a significant challenge. Installers require training in termination, inspection and cleaning, and the conditions found in industrial applications limit the practical use of fibre and its considerable capabilities for high-speed communication.
Introducing Expanded Beam
Expanded beam technology offers a solution to these challenges. An expanded beam connector uses a lens to enlarge the optical signal into a collimated beam. The light rays within a collimated beam travel along a parallel path and do not spread out. The beam then moves across an air gap, after which it can be refocused into the receiving fibre using another lens.
The advantage of this process is that the beam is far larger than the tiny core of the fibre itself and is not reliant on perfect physical contact. Both mating fibre ends are behind the lenses, protecting them from harm. An expanded beam connector is therefore far more able to withstand the demands of harsh environments. Mating fibres are protected against the wear and tear of repeated connection cycles or accidental impacts.
The collimated beam itself is far more tolerant of dust and debris between the mating faces of the lenses, and in many cases the mating face of the connector can be cleaned without the need for specialist equipment. The result is a connector that is far more robust than a traditional fibre solution, enabling it to be used in tough conditions.
Expanded beam connectors offer solutions for field-based applications that operate in environments where maintaining precise fibre alignment is impossible. Applications such as smart agriculture and renewable energy installations require high-speed communications for fixed installations, but expanded beam connectors are also suitable for deployable infrastructure. Whether used for outside broadcast equipment or to create temporary networks for disaster recovery operations, expanded beam technology allows rapid deployment of high-speed communications without the need for specialised training or delicate handling.
Bulgin has introduced expanded beam technology into its range of Buccaneer circular connectors.
By combining robust fibre functionality with the proven reliability of the Buccaneer series, Bulgin has created a connector that makes the performance of optical systems accessible to a wider range of industries and applications.
The high-impact polymer housings are sealed to IP68, providing protection against tough conditions and retaining the familiarity of the popular Buccaneer design.
Conclusion
Optical fibre is a vital component in the demand for global connectivity, but harsh environments demand more resilient solutions. Expanded beam technology meets this challenge with robust connectors that ensure high-speed communication in the field. By eliminating the need for precise alignment or delicate handling, it enables faster deployment and wider adoption of high-speed connectivity. Bulgin’s combination of proven connector solutions and robust optical design ensures that expanded beam connectors are an important addition to the installer's toolbox.
