Where should I use which fiber patch cord connector?

A large number of fiber optic transceivers are available in the market. Each of the SFP transceiver has different requirement of the fiber patch cord connector that can be inserted in it for proper use. In this article we will study in detail about the connectors that can be connected to different types of fiber optic transceivers available in the market. To understand the fiber optic connectors, we should know about the basic structure of a fiber optic patch cord. Figure 1 shows the different components of a fiber optic patch cord.

- 1. Fiber optic patch cord connector 1
- 2. Fiber cable
- 3. Fiber optic patch cord connector 2

It is evident from figure 1 that a typical fiber optic patch cord has a specific length of single-mode or multi-mode fiber cable and two connectors. One of these connectors is installed in the communication equipment and the other connector is installed in either the other end’s communication equipment or the optical distribution frame (ODF). Different types of fiber optic patch cords are used in both cases.

SFP transceivers, which are the most widely used fiber optic transceivers use LC connector, whereas the GBIC transceivers use the SC connector. Similarly, other connectors, such as FC, ST, and MT-RJ are also used for their particular applications.

Transceiver Type Connector Type
- SFP - LC
- SFP+ - LC
- XFP - LC
- GBIC - SC
- DWDM Systems - E-2000
- GPON/EPON - SC

Table 1: Fiber Optic Connector Applications Table 1 illustrates the type of connectors used for some of the common applications. In the next section, we shall study about the construction and physical characteristics of the different fiber optic connectors.

LC Connector
LC connector is the most compact connector with only 1.25mm ferrule diameter. LC patch cords are available in single-mode and multi-mode fibers. Furthermore, simplex and duplex versions are also available. Simplex LC patch cords are used in Bi-Directional SFP transceivers whereas duplex patch cords are required for SFP or SFP+ transceivers. Figure 2 shows the simplex LC connector.

SC Connector
SC connector is also a widely used fiber optic patch cord connector, GBIC transceivers use the SC connectors. SC connectors are also used commonly in optical distribution frames. SC connectors are double the size of an LC connector, i.e., the ferrule diameter of an SC connector is 2.5mm for simplex connector. Figure 3 shows a duplex SC connector.

ST Connector
ST connector is another widely used fiber optic connector. ST connector was developed by AT&T. It is primarily used with multi-mode fiber optic cables. ST connectors are twist-locking connectors, having a round ferrule of 2.5mm diameter. ST patch cords are available with both simplex and duplex ST connectors depending on the application. ST connectors are extensively used in telecommunication related equipment. Figure 4 shows an ST connector.

It is not necessary to have the same fiber optic connectors on both ends of a fiber optic patch cord. Fiber optic patch cords are available in various combinations such as LC-SC, LC-ST, etc. Choice of connector at either end of the fiber optic patch cord is purely dependent on the type of transceiver or optical distribution frame it is being terminated on. Usually, the supported connector is mentioned in the product literature or installation manual. It is advisable to read the product documentation before ordering any patch cords.