Fibre optic connector that comes in various configurations and types is considered as an important component for the fibre optic cable. Generally speaking, different fibre cable connector types can be categorized according to different standards like the utilization, fibre count, fibre mode, transmission method, transmission media, boot length, polishing type termination way, etc. In this article, you will become familiar with the various types of fibre connectors, helping you make the right choice when purchasing in the future.
Common types of fibre connectors
The following five fibre connectors are the most commonly used. They are introduced below in order of popularity, from the most widespread to the most commonly used. Fibre cables with these optical connector types are usually used in data centres, telecom rooms, enterprise networks and so on.
LC Connector
A Lucent Connector (LC), as one SFF (small form factor) connector, possesses a 1.25 mm ferrule. The small footprint design gives these fibre optic connectors huge popularity in datacoms and makes them ideal for high-density applications. Many tend to move to high-efficiency cabling with LC fibre connectors nowadays. LC fibre optic connector is considered the most commonly used connector at present.
SC Connector
SC fibre connector was the first connector chosen for the TIA-568 standard and is a snap-in connector that latches with a simple push-pull motion. “SC” stands for “Square Connector” due to the “square-shaped” connector body. It adopts a 2.5mm ferrule, which is twice the size of the previous LC connector. SC fibre optic connector is ideally suited for datacoms and telecom applications including point-to-point and passive optical networking. Due to its excellent performance, the fibre optic SC connector remains the second most common connector for polarisation-maintenance applications.
MTP/MPO Fiber Connector
Unlike the previous two fibre optic connectors, the MTP/MPO fibre connector is a multi-fibre connector and larger than other connectors, which combines fibres from 12 to 24 fibres in a single rectangular ferrule. It’s often used in 40G and 100G high-bandwidth optical parallel connections. The MTP/MPO fibre connectors are complicated due to the key-up and key-down, male and female issues. You can refer to our white paper Understanding Polarity in MTP/MPO System to have a better understanding.
ST Connector
ST (Straight Tip) fibre optic connector was created and licensed by AT&T shortly after the arrival of the FC type. The ST optic connector holds the fibre with a ceramic, spring-loaded 2.5mm ferrule that stays in place with a half-twist bayonet mount. They are usually used in both long and short-distance applications such as campuses and building multimode fibre applications, corporate network environments, as well as military applications.
FC Connector
“FC” refers to the Ferrule Connector. FC fibre optic connector was the first optical fibre connector to use a ceramic ferrule. Unlike the plastic-bodied SC and LC connector, it utilizes a round screw-type fitment made from nickel-plated or stainless steel. The FC fibre optic connector end face relies on an alignment key for correct insertion and is then tightened into the adaptor/jack using a threaded collet. Despite the additional complexity both in manufacturing and installation, the FC connectors still provide the choice in precision instruments such as OTDRs, as well as the choice for single-mode fibre. It was initially intended for datacoms and telecoms applications but has been used less since the introduction of the SC and LC fibre optic connectors. The usage of both ST and FC connectors has declined in recent years.
The figure below shows the different connector styles:
Less common types of fibre connectors
The following fibre connectors are less commonly used; some are only utilised in specialised connection scenarios, while others have been phased out and are no longer in use.
MT-RJ Connector
Mechanical Transfer Registered Jack (MT-RJ) connector is a duplex connector that uses pins for alignment and has male and female versions. Constructed with plastic housing and provide for accurate alignment via their metal guide pins and plastic ferrules. Compared to a standard phone jack, the size of the MT-RJ connector is slightly smaller, making it easier to connect and disconnect. In addition, the MT-RJ fibre optic connector provides a lower termination cost and greater density for both electronics and cable management hardware compared to other singer-fibre terminations.
MU Connector
Like a miniature SC with a 1.25mm ferrule. Featuring a simple push-pull design and compact miniature body, the MU fibre optic connector is used for compacting multiple optical connectors and a self-retentive mechanism for backplane applications. You can get a customized high-power MT-RJ/MU fibre optic connector in FS.
DIN Connector
The DIN connector is round with pins arranged in a circular pattern. It encompasses several types of cables that plug into an interface to connect devices. Typically, a full-sized DIN connector has three to 14 pins with a diameter of 13.2 millimetres. It is applied to PC keyboards, MIDI instruments, and other specialized equipment.
E2000 Connector
The E2000 Connector is a push-pull coupling mechanism with an automatic metal shutter in the connector for dust and laser beam protection. One-piece design for easy and quick termination, the E2000 fibre optic connector is used for high safety and high power applications.
VSFF Connector
VSFF (Very Small Form Factor) connectors are compact fibre-optic connectors designed to save space while increasing port density, particularly in data centres. These connectors enable higher port densities by being smaller and more efficient than traditional connectors like the LC duplex. The three most common types of VSFF connectors are the CS®, SN®, and MDC connectors.
CS® Connector: The CS connector (Compact Small-form-factor) is an ultra-compact dual-fibre connector designed by SENKO. Its design is similar to that of the LC connector but with a smaller footprint. It is 40% smaller than the LC duplex, offering more space for cable management and improving airflow within the rack.
SN® Connector: Developed by SENKO, the SN connector (Senko Connector) offers high data rates and a compact form factor suitable for dense installations. With an automatic dust cover and a locking mechanism, it ensures excellent performance and reliability. It is compatible with 1.25mm ferrules and provides an upgrade path to 400G and beyond, with fibre density three times that of duplex LC.
MDC Connector: The MDC is a compact duplex connector introduced by US Conec, with a pin pitch of just 3.1mm. It utilises a 1.25mm industry-standard ferrule and offers a density three times that of LC connectors. The MDC is the specified optical connector interface for QSFP-DD and SFP-DD transceiver MSAs. On FS.com, you can buy the MDC Fiber Optic Cable with VSFF connector. It maximises 200G/400G data centre density utilisation.
D4 Connector
The D4 fibre optic connector is an early fibre optic connector, typically used for multiplexing and demultiplexing optical signals. It features a round metal housing with four fibre channels inside. The D4 connector is equipped with precise alignment mechanisms in both the plug and socket to ensure accurate fibre end-face alignment, thereby reducing insertion loss and return loss. Compared to modern fibre optic connectors, such as LC or MTP/MPO, it is significantly larger. It is therefore superseded.
ESCON Connector
In the early 1990s, IBM developed Enterprise Systems Connection (ESCON), a serial, half-duplex optical interface designed for single-mode fibre systems. ESCON aimed to improve connectivity by integrating fibre optics into networks. The ESCON fibre connector uses a 2.5mm ferrule and pairs with SC or ST connectors via fibre adapters. However, ESCON connectors have gradually been replaced by more advanced connectors, such as Fibre Channel and other high-performance fibre interface standards.
FDDI Connector
The FDDI connector (Fibre Distributed Data Interface) was developed by the American National Standards Institute. It features an automatic dust cover and locking mechanism, along with a floating alignment structure, blind-mate design, and locking system, all of which provide excellent performance and reliability. The FDDI connector is also known as the MIC (Media Interface Connector).
Fibre Connectors Connect Without Adapter Panel
Compared to the above fibre optic connector types, Rosenberger Q-RMC and NEX10 connectors adopt a push-pull quick locking mechanism, which can realize quicker connection without using an adapter panel. They are designed for harsh environmental use.
Rosenberger Q-RMC Connector
Q-RMC, short for Rosenberger Multifiber Connector, is a new and robust industrial connector with the multi-fibre MT ferrule of the MTP®/MPO connector that can hold 24 fibre cores. This kind of very small form factor connector includes a push-pull closing mechanism, which makes the optic connector to be connected simpler and quicker even in tight areas, thus reducing installation times and the associated costs. The Q-RMC connector fulfils the requirements for protection class IP67, so it is waterproof, dustproof and resistant to corrosion. What’s more, the Q-RMC connector is suitable for use in areas with extreme temperatures thanks to its operating and storage temperature is up to -40~80℃. So, fibre cables with Q-RMC connectors can be used for industrial sites, minefields, mobile communication (FTTA), 5G Base stations, broadcast, smart grid cabling and so on.
Rosenberger NEX10 Connector
The Rosenberger NEX10 connector is suitable for an outdoor environment, and it is characterized by a compact size design plus waterproof, dustproof and anti-corrosion. This connector type supports a screw-type and a push-pull locking mechanism. The push-pull quick lock helps in achieving solid installation and easy removal without any tools. For the screw-type plug, there is a screw-locking mechanism, ideal for the plug and socket to keep a firm connection. Nowadays, FS introduces the industrial fibre optic patch cable with Rosenberger NEX10 connectors and its operating & storage temperature for connectors & outdoor cables lie between -40~80℃, which is often used in industrial sites, minefields, small sales, distributed antenna systems(DAS), In-building architecture, and MIMO.
Both single-mode and multimode Q-RMC/NEX10 connectors are available in FS. You can also choose an optical fibre type cable jacket according to your needs to get a customized industrial fibre optic cable.
Fiber Count: Simplex vs Duplex Fiber Connectors
A simplex connection means signals are sent in one direction—a signal is transmitted through two simplex connectors and a simplex fibre cable from device A to device B, which cannot return from device B to device A via the same route. Contrariwise, the revised transmission can be achieved through duplex connectors and duplex fibre cable, which is called a duplex connection. In addition, a simplex fibre optic connector is often connected with one strand of glass or plastic fibre, while the duplex fibre optic connector needs to connect with two strands of fibres.
Fiber Mode: Single Mode vs Multimode Fiber Connectors
Single-mode fibre allows only one light mode to pass through at a time, while multimode fibre can propagate multiple modes at a time. Diversity has an impact on single-mode fibre connectors and multimode fibre connectors on account of the combination with the corresponding type of optical fibre. However, with technologies getting advanced, fibre optic connectors like SC, LC, and FC, provided by fibre optic connector factories are compatible with single-mode and multimode fibre cables.
Boot Length: Standard Boot vs Short Boot Connectors
As for the boot length, there are standard boot structures and short boot structures. A standard boot can protect the cable and the connector from being damaged, wires being dislodged from the connector body, etc. While a short boot has the same function, it is distinguished by a shorter boot structure. For places where there is limited space for connectors, short boot cables can be the ideal choice. The short boot structure design can make the cable easily pass through the narrow space without sacrificing performance, making the installation and maintenance of the fibre optic cables more efficient.
FS offers high quality short boot fiber optic patch cables. Precision zirconia ferrule connectors ensure low loss with bend-insensitive fibers with a minimum bend radius of 7.5mm, a 60% reduction in boot length and a 30% reduction in overall connector length. They are ideal for high-density cabling applications where space is at a premium.
Polishment: APC/PC/UPC Fiber Optic Connectors
According to the polishing type, optical fibre cable connectors can be divided into three types: PC, UPC, and APC connectors. The colour code provides a convenient method to identify these three types of connectors: the PC’s colour code is black, the colour code for the APC fibre connector is green, and the UPC’s connector is blue. The structure and the performance of the three fibre optic connectors also vary, which reflects the values of insertion loss and return loss. PC vs UPC vs APC. This article sheds light on these connector types and their differences for you.
Termination: Field-terminated vs Pre-terminated Fiber Connectors
Field termination, as its name implies, is to terminate the end of the fibre in the field. The procedure includes stripping the cable, prepping the epoxy, applying the connector, polishing, inspecting and testing for the connection, requiring not only a large number of tools but also skilled technicians to conduct the termination.Factory termination, also called factory pre-termination, refers to cables and fibres terminated with a connector in the factory. The pre-terminated cables come in pre-measured lengths with the fibre optic connectors already installed with factory-level precision and quality assurance. Reducing the cumbersome process and tools, factory pre-terminated solutions are easier to install and require less technical skills.
How to Choose Different Fibre Optic Connector Types
After understanding the many types of fibre optic connectors, there are several factors to consider when choosing a fibre optic connector type. Different connector types are suitable for different needs, so careful comparison and analysis are required when making a selection.
Performance Characteristics
Connector types can vary in transmission performance, with certain ones being ideal for long-distance transmission and others better suited for short-range use. Therefore, it is essential to determine the necessary transmission performance based on actual requirements when selecting a connector.
Applicable Scene
The applicable scene is also an important consideration in selecting the connector type. For example, in the data center environment, you may need to use high-density connectors to meet the needs of a large number of fiber optic connections; and in outdoor or harsh environments, you need to choose a connector with waterproof and dustproof features. SC/APC connectors may be preferred in passive optical networks (PONs) for their ability to offer higher return loss, thereby aiding in the prevention of signal reflection. On the other hand, in fibre distribution systems catering to a large number of subscribers, MTP/MPO connectors may be more appropriate due to their support for high port density connections.
Cost
Different types of connectors may have different manufacturing processes, material costs, etc., so the relationship between performance and cost needs to be weighed when choosing.
Compatibility
Various devices might be designed to work with certain types of connectors. It’s important to take into account the compatibility with current device interfaces when choosing a connector. For instance, while some devices may typically use LC connectors, others might rely on SC connectors, making it vital to maintain connector uniformity in network design.
By carefully considering these factors, you can ensure that the selected connector provides optimal performance and reliability in specific scenarios.
FS offers a variety of fibre optic connectors along with customisation services to meet the needs of different users. Copper cables, various fibre cleaning and testing tools, and patch panels are also available for purchase in the FS online store. Additionally, the FS expert team can create tailored cabling solutions to help you swiftly upgrade your network equipment.
conclusion
In conclusion, fibre optic connectors play a crucial role in the world of optical communications. Each type of fibre optic connector has its unique characteristics and applications. When selecting and using them, it is important to make appropriate choices based on specific requirements and conditions.
