Optical fused couplers play an important role in telecommunication applications. Basically, they are passive fiber optic couplers that help you with the redistribution of optical signals. They are named so because they are formed by two optical fibers that are twisted, stretched, and fused together so that the two cores remain very close. In general, fiber optical couplers cover different fiber optics devices, such as optical splitters, optical combiners, and optical couplers based on how they are used.
The main purpose of a fiber optic coupler is to distribute the optical signal from input fiber among two or more fibers (optical splitter) or combine the optical signal coming from two or more fibers into a single fiber (optical coupler).
Since the input signal is not directly transmitted from one fiber to another fused optical coupler and is divided among the output ports, optical signals are usually more attenuated in an optical coupler than in a connector or a splicer. For instance, with a 1 x 2 fused optic coupler, each output is less than half the power of the input power.
Based on their shape, fused optical couplers are available in Y, T, X, star, and three variants. Let’s find out how these different fused optical couplers work.
How does a Y coupler work?
As the name suggests, the Y coupler takes input signals from two fibers and then combines the signals into one and transmits them into one fiber. Since it resembles the shape Y, it is called a Y coupler. If it takes one input signal and redistributes it into two signals to be transmitted into two different output fibers, it is called a Y splitter. This coupler is also known as an optical tap coupler. The good thing is the optical power distribution can be controlled precisely to meet the users’ specific applications.
How does a T coupler work?
A T coupler redistributes power unevenly. Contrary to the Y coupler, the power of one output signal is greater than the power of another output signal. The common power splitting ratio is 10:90 and 20:80.
How does an X coupler work?
Also known as a 2 x 2 coupler, it does the function of a splitter and a combiner in one package. So, it not just combines but also divides the optical power from the two input fibers between the two output fibers.
How does a star coupler work?
A star coupler usually has multiple input and output ports and the output is distributed from more than two input ports among various output ports. In this configuration, the number of input and output ports may or may not be equal in star couplers. So, you can find them in various configurations such as 2 x 4, 4 x 4, or 8 x 16. However, the distribution of power among output ports remains equal.
How does a tree coupler work?
Also called a multiport coupler, this type of coupler splits optical power from one input fiber to more than two output fibers and can also work in the reverse direction to combine the optical power from different input fibers into one output fiber.
Optical fused couplers are not only widely used in telecommunication applications but also in network LAN applications where these couplers are used in either bus architecture or star architecture. Plus, they are also used in CATV, FTTH, and testing applications.
