There is a wide variety of fiber optic connectors, with the mainstream types including SC, LC, ST, FC, MTP/MPO, and E2000 connectors, as well as many variants and specialized connectors, especially in data centers and specific applications.
SC and ST connectors were among the first fiber optic connectors to appear, while the subsequent introduction of LC connectors enabled smaller and more compact connections. With the rapid development of the internet and data communications, the emergence of multi-fiber connectors like MTP/MPO has further promoted the use of fiber optics in data centers and high-bandwidth applications. The technology behind fiber optic connectors continues to advance, evolving to meet the demands for higher bandwidth, lower latency, and greater reliability.
Below is a chart of common fiber optic connector types, covering some important parameters and characteristics related to them.
Fiber Optic Connector Types Chart
| LC Connector | SC Connector | ST Connector | FCConnector | MTP/MPO Connector | E2000 Connector | HFOC Connector | |
| Image |  |  |  |  |  |  |  |
| Full name | Lucent Connect Connector | Subscriber Connector or Square Connect Connector | Straight Tip Connector | Ferrule Connector or Fiber Channel Connector | Multi-Fiber Push-On/Pull-Off Connector | E2000 or Latching Interface System or LIS Connector | Hardened Fiber Optic Connectors |
| Ferrule Size | 1.25 mm | 2.5 mm | 2.5 mm | 2.5 mm | 2.5mm, Supports up to 24 fibers in a single ferrule | 1.25 mm | 2.5 mm ceramic ferrule |
| Coupling Mechanism | Latch (push-pull) | Snap-in (push-pull) | Bayonet twist-lock | Screw-on | Push-pull (multi-fiber) | Push-pull with integrated dust cover | Various outdoor-rated designs |
| Single-mode / Multi-mode | Single-mode and multi-mode fiber applications are both very common. | Single-mode and multi-mode fiber applications are both very common. | Commonly found in multi-mode fiber applications. Can be used for single-mode, but less frequently. | Primarily suitable for single-mode fiber. Can also be compatible with multi-mode fiber. | Suitable for both single-mode and multi-mode fiber. | Mainly used for single-mode fiber. Can also be applied to multi-mode fiber. | Applicable to both single-mode and multi-mode fiber, with the specific choice depending on application requirements and fiber type. |
| Polishing Type | UPC or APC (usually UPC) | UPC or APC (commonly UPC) | Typically UPC | UPC or APC (commonly UPC) | Usually UPC, but can also be APC | Typically APC | Usually UPC, but APC may also be used depending on the specific design. |
| Applications | High-density installations, data centers, telecom | Datacom, telecom, passive optical networks (PON) | Campus networks, multimode fiber applications, military uses | High-vibration environments, measurement equipment like OTDRs | Data centers, high-speed networks (40G/100G), parallel optics | Telecom wide area networks (WAN) | Outdoor fiber-to-the-home (FTTH) deployments |
| Advantages | Compact size, ideal for high-density environments, commonly used in SFP transceivers | Simple push-pull design, robust and easy to use | Durable and reliable for field installations | Secure connection with threaded coupling, good for single-mode fibers | High fiber density, fast deployment for large-scale installations | Integrated dust cover protects the ferrule from contamination | Designed for harsh environments with protection against water and dust |
| Usage | LC connectors are the most widely used today due to their small form factor and efficiency in high-density cabling applications | Once the dominant connector type, SC connectors are still widely used but have been gradually replaced by LC connectors in many high-density applications | ST connectors were popular in the past but have seen a decline with the rise of LC and SC connectors | Mostly used in specialized applications like testing equipment due to its secure fit | MTP/MPO connectors are increasingly popular in data centers due to their ability to handle multiple fibers at once | Primarily used in telecom environments where reliability is critical | Commonly used in broadband network access and drop applications |
Understanding the types of fiber optic connectors helps us gain a better insight into them, enabling us to make the right choices.
Fiber Optic Connector Types
Fiber optic connectors can be classified in various ways based on different applications and parameter information. The terms like LC and ST mentioned above refer to the classification based on the type of fiber interface used in the equipment.
SC Connector: SC stands for “Subscriber Connector” or “Standard Connector.” It is a plug-and-pull connector that is popular for its simple insertion and removal mechanism. Its housing is made from molded fiberglass plastic in a rectangular shape. The SC connector uses a push-pull latching mechanism, requiring no rotation, making it easy to use, cost-effective, and exhibiting low insertion loss variation with high compressive strength.
ST Connector: ST stands for “Straight Tip.” It was commonly used in early fiber optic networks, particularly in multi-mode fiber applications. The most notable feature of the ST connector is its straight sleeve, a rigid plastic tube that holds the fiber in place for proper alignment during interconnection or termination. ST connectors are spring-loaded, allowing for easy insertion and removal.
LC Connector: LC stands for “Lucent Connector,” originally developed by Lucent Technologies. Its compact design is suitable for high-density applications, often used in data centers. It features a modular RJ-style latch mechanism for easy operation. The size of the pins and sleeves in LC connectors is 1.25 mm, which is half the size of standard SC or FC connectors.
FC Connector: FC stands for “Ferrule Connector.” It has a metal housing and is equipped with a threaded locking mechanism, commonly used in high-performance and high-reliability applications.
MTP/MPO Connector: MTP (Multifiber Termination Push-on) and MPO (Multi-Fiber Push-On) connectors are both multi-fiber connectors designed for high-density cabling. MTP is an improved version of MPO, typically offering better performance.
E2000 Connector: The E2000 connector originates from European standards and offers excellent optical performance, suitable for high-density and high-bandwidth applications.
HFOC Connector: HFOC stands for “High Fiber Optical Connector,” primarily used for high-density fiber connections and commonly found in specific industries.
When it comes to different types of fiber optics, there are various options for fiber connectors: single-mode fiber connectors and multi-mode fiber connectors.
Single-mode fibers typically have a smaller core diameter of about 8-10 microns. They allow only one mode of light to propagate through the fiber, making them suitable for high-bandwidth applications and capable of supporting high-speed data transmission. Common standards include OS1 and OS2, with OS2 generally used for outdoor long-distance applications.
Tip:
- OS1: Optical Single-mode 1, with a core diameter of about 9 microns. Suitable for indoor applications, primarily used for telecommunications and data center connections. It supports longer transmission distances, typically up to 10 kilometers or more, depending on the equipment and wavelength used.
- OS2: Optical Single-mode 2, also with a core diameter of about 9 microns. It optimizes fiber design to reduce signal attenuation, generally offering better performance standards. It supports longer transmission distances, typically up to 40 kilometers or more.
Multi-mode fibers have a larger core diameter, usually 50 microns or 62.5 microns. They allow multiple modes of light to propagate through the fiber. Due to the propagation of multiple modes, signal attenuation is higher, making them suitable for short-distance transmission, typically ranging from a few hundred meters to a few kilometers. They are commonly used in local area networks (LANs), data centers, and short-distance communications. Common standards include OM1, OM2, OM3, and OM4, with higher numbers supporting greater bandwidth and transmission distances.
Tip: OM1, OM2, OM3, and OM4 are different categories of multi-mode fibers.
- OM1: Optical Multi-mode 1, with a core diameter of 62.5 microns. Typically supports a maximum transmission speed of 1 Gbps at a wavelength of 850 nm, with a transmission distance of about 275 meters.
- OM2: Optical Multi-mode 2, with a core diameter of 50 microns. Supports a maximum transmission speed of 1 Gbps at a wavelength of 850 nm, with a transmission distance of up to 550 meters.
- OM3: Optical Multi-mode 3, with a core diameter of 50 microns. Supports a maximum transmission speed of 10 Gbps at a wavelength of 850 nm, with a transmission distance of up to 300 meters.
- OM4: Optical Multi-mode 4, with a core diameter of 50 microns. Supports a maximum transmission speed of 10 Gbps at a wavelength of 850 nm, with a transmission distance of up to 400 meters.
Based on the outer jacket diameter of the fiber, common types of fiber connectors include: 0.9 mm fiber connectors, 2.0 mm fiber connectors, and 3.0 mm fiber connectors.
- 0.9 mm fiber connectors are commonly used for indoor fiber, suitable for general wiring and connections.
- 2.0 mm fiber connectors are typically used for outdoor fiber, providing better protection and durability.
- 3.0 mm fiber connectors are also used for outdoor fiber, suitable for applications requiring higher mechanical strength.
Based on the end-face polishing types of fiber optic connectors, there are UPC fiber optic connectors, APC fiber optic connectors, and PC fiber optic connectors.
The end-face polishing of fiber optic connectors is a crucial factor affecting the quality of optical signal transmission.
The ferrule is the housing at the exposed end of the fiber, which holds the fiber in place and helps with alignment. Ferrules can be made from plastic, ceramic, metal, or glass, and are typically cylindrical with a hole in the center. When a connector is installed on the end face of a fiber optic cable, reflection from the light source leads to some unavoidable return loss. Significant light loss can damage the laser source and disrupt signal transmission. To improve contact between the end faces of two fibers, the end face of the fiber jumper is usually polished to different structures.
The PC (Physical Contact) connector features a more traditional polishing method, providing decent surface contact but having higher return loss compared to UPC and APC. It is suitable for applications where performance requirements are not as critical.
The UPC (Ultra Physical Contact) connector features a highly polished end face, resulting in a smooth surface that allows for more precise mating and reduced return loss. It is widely used in applications requiring low-loss connections, such as data centers and high-performance computing environments. UPC is an upgrade from the PC (Physical Contact) connector. Typically, PC/UPC connectors are blue in color.
The APC (Angled Physical Contact) connector features a 30-degree angled end face, which allows for a tighter contact between fiber ends. This design directs light reflection into the cladding rather than back to the light source, effectively reducing reflection and further minimizing return loss. APC connectors are particularly suitable for high-bandwidth and high-frequency applications, commonly used in single-mode fiber and high-demand communication systems. Typically, APC connectors are green in color.
APC fiber optic connectors are better suited for applications requiring high-precision optical signal transmission. They are commonly used in CATV and other optical RF applications across a wide wavelength range, as well as in passive applications such as PON network structures or passive optical LANs.
For applications that are less sensitive to fiber optic signals, UPC fiber optic connectors can be chosen. They are typically used in Ethernet network devices (such as ODF fiber patch panels, media converters, and fiber switches), as well as in digital, cable television, and telephone systems.
Due to the angled end face of APC connectors, they cannot be connected to UPC connectors, as this would lead to a decrease in connector performance. However, both PC and UPC fiber end faces are flat, differing primarily in the quality of the polish. Therefore, mixing PC and UPC connectors does not cause permanent physical damage to the connectors.
According to the way optical signals are transmitted, fiber optics can be classified as simplex and duplex, which also distinguishes the types of fiber connectors: simplex fiber connectors and duplex fiber connectors.
Simplex refers to signals that can only flow in one direction. For example, in applications such as broadcasting and the connection of certain sensors to control systems, where data is transmitted unidirectionally. Therefore, simplex fiber connectors typically connect to only one fiber, making them suitable for one-way applications.
Duplex refers to signals that flow in both directions, allowing simultaneous sending and receiving. For instance, in phone calls, Ethernet, fiber switches, and other data center devices. As a result, duplex fiber connectors usually connect to two fibers, one for sending and the other for receiving.
Based on the length of the external boot, fiber connectors can be classified into standard boot connectors and short boot connectors.
Standard boot connectors typically have a longer boot , providing greater protection and mechanical strength. They are suitable for environments that require higher durability and protection, such as data centers, industrial applications, or other harsh conditions. Their longer boot makes them more flexible in managing and protecting the fiber.
Short boot connectors, on the other hand, have a shorter boot and are usually used in space-constrained environments. They are suitable for high-density cabling or applications that require compact spaces, such as racks or fiber patch panels. This design helps save space and improves wiring efficiency.
In summary, we have categorized fiber connectors based on multiple dimensions to help you better choose the most suitable fiber connector for your needs and applications.