Fiber optic coupler is one type of fiber optic component that allows for the redistribution of optical signals. It covers a wide range of fiber optic devices such as optical splitters, optical combiners, and optical couplers. A fiber optic coupler is a device that can distribute the optical signal from one fiber among two or more fibers, or combine the optical signal from two or more fibers into a single fiber.
Usually, optical signals are attenuated more in an optical coupler than in a connector or a splice because the input signal is not directly transmitted from one fiber to another, but divided among the output ports. For instance, with a 1 x 2 fiber optic coupler, each output is less than one-half of the power of the input signal (over a 3dB loss).