Optical fiber has become increasingly popular, providing high-speed, reliable data transfer and communications for a huge range of applications. As well as the fiber itself, it’s important to pick the right connectors for the job, but navigating through the multiple options that are available can be confusing.
In fact, there are three types of fiber connectors in common usage: SC, ST (bayonet-twist) and LC (push-pull locking). The most frequently specified is the LC connector, the most suitable for space-constrained applications as it is much more compact than the other two – not only that but because it provides a secure clip connection, there is much less of a chance of the fiber accidentally disconnecting.
Simplex or duplex?
Also up for consideration is another additional complication: fiber optic LC connectors are available in simplex and duplex options. What does that mean? Let’s break it down. A simplex optical fiber is only capable of transmitting data in one direction as it only uses a single strand of glass or plastic fiber. This means that this type of fiber is perfect for applications in which uni-directional capability is needed. For example, transmitting data from a sensor in an Internet of Things (IoT) system. Therefore, a duplex optical fiber can transmit data in both directions as it consists of two strands of fiber. A duplex optical fiber also has two variants. It might be ‘half duplex’ which only sends data in one direction at a time, or it may be ‘full duplex’ which handles simultaneous, bi-directional communications. More obvious than not, simplex fibers cost less than duplex fiber thanks to the use of one fiber and not two. It should also be noted that both simplex and duplex fibers are available as either single mode or multimode versions, depending on the needs of any particular use case.
(4000 Series Fiber simplex connector and 6000 Series Fiber duplex connector)
Connectors for harsh environments
Once the type of fiber that will be used has been chosen, the appropriate LC connecter that matches the fiber needs to be specified – simplex or duplex? For some applications, a standard LC connector will be suitable but as fiber use is on the increase, this means outdoor applications are on the increase too. The use of fiber in outdoor installations and harsh environments means that delicate optical fiber is at risk from moisture, dust and dirt which can in turn affect the transmission of light which then affects the data rates achieved. Although the fibers themselves are protected by an acrylic layer, the connectors can be vulnerable in outdoor usage. In the most extreme situations, water could gain access inside a connector and freeze. This can cause damage to the fiber which has the potential to cease and communication. Standard LC connectors, however, are not rugged enough for harsh environments which means that it cannot be guaranteed that water or moisture will not make its way into the connector. You could use a custom enclosure to protect the connector, but this can prove expensive and large in size. More often than not, too expensive and too big. A better answer is to specify a rugged LC connector, such as the 4000 series fiber range from Bulgin, which provides an industry-standard LC interface as specified by IEC 61754-20. This connector protects the ends of the optical fiber from dirt and damage, and provides a seal to prevent any ice forming. The fiber connection provided by the 4000 series is UV resistant, salt spray resistant and sealed to IP66, IP68 and IP69K. It also provides a secure quick twist bayonet connection, ensuring durable mechanical mating. The connector operates over a wide operational temperature range of -25 to 70ºC, with an average insertion loss of less than 0.1dB and a maximum insertion loss of 0.2dB.
Visit Bulgin’s Connectivity Community for expert advice on optical fiber connectors and installations in harsh environments.