Introduction to Fiber Optic Adapter

As we know, fiber optic connector is an important fiber optic component used to connect two fiber optic lines together. Apart from connector, there is also another important optical component — fiber optic adapter. Fiber optic adapter, sometimes also called coupler, is a small device designed to terminate or link the fiber optic cables or fiber optic connectors between two fiber optic lines. Here I’d like to introduce some basic knowledge about fiber optic adapters.


Fiber optic adapters are typically connecting cables with similar connectors such as SC adapter to SC connector, LC adapter to LC connector and so on. Some adapters, called “hybrid”, can link different types of connectors, for instance, ST to SC or LC to SC. When attempting to connect two cables with different connector types, it is necessary to use a hybrid adapters.

There are also adapters that can be used to attach a bare fiber optic cable to a power adapter. This piece allows the cable to fit into a connection slot, whether into a mating sleeve or into an electronic device. The fiber-optic cable can be fit into an adapter that works with any of the standard shaped connectors.


By linking two connectors precisely, fiber optic adapters allow the light sources to be transmitted at most and lower the loss as much as possible. At the same time, fiber optic adapters have the merits of low insertion loss, good interchangeability and good reproducibility.


There are various kinds of fiber optic adapters according to different standards. As we all known, in one complete cabling system, the fiber optic adapter panel shapes or types should be in accordance with the fiber optic connectors or cables to make sure the fluent fiber optic connection. Therefore, fiber optic adapters have different classifications.

Connector types

According to the connector types, fiber optic adapters can be divided in to FC-FC, SC-SC, LC-LC, ST-ST, MTRJ, etc. Common shapes of the adapters are square, rectangular, or round. These simple types of adapters are often referred to as mating sleeves because they allow two cables to connect to one another. Some of these common line to line connectors are also built to connect three or four cables together.

Polish type

According to polish type, there are PC, UPC and APC fiber optic adapters. Generally, PC and UPC adapters are designed with blue, and APC are green. It’s known to us that whenever a connector is installed on the end of fiber, loss cannot be avoided. Some of this light loss is reflected directly back down the fiber towards the light source it generates. These back reflections, or optical return loss (ORL), will damage the laser light sources and also disrupt the transmitted signal. Therefore, various polish profiles are used, but it depends on the type of fiber and the application. Generally speaking, a typical hand polished connector will measure at 30 dB.

Fiber type

According to fiber type, fiber optic adapters have single-mode and multimode. The single-mode adapters offer more precise alignment of the tips of the connectors. It’s no problem to use single-mode adapters to connect multimode cables, but it’s better not use multimode adapters to connect single-mode cables, for such connection can cause misalignment of the small single-mode fibers and increase attenuation.

Fiber count

According to the fiber count, optical adapters can be classified into simplex, duplex and quad. Simplex fiber optic adapters usually connect single fibers together, and duplex adapters link two fibers together. Under some occasions, four fibers needed to be connected, then quad fiber adapters can be applied.


As the life pace is getting more and more fast, there is an increasing needs for high speed information transmission. From the above description, we have got an overview about fiber optic adapter. A single optical fiber adapter maybe hold a dozen of cables. If we splice multiple adapters together, it can even make hundreds or thousands of connection. As long as we know what kind of connections, multimode or single mode, simplex or duplex as well as the connector types, we can try to make fiber optic adapters play an more important role in our daily cabling systems.

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