Fused Coupler

A fused coupler basically consists of two, parallel optical fibers that have been twisted, stretched and fused together so that their cores are very close to each other. The length of this coupling region determines the coupling ratio from one fiber to the other. During the manufacturing process, light is launched into an input fiber and the output power from each output fibers is carefully monitored. When the desired coupling ratio is achieved, the fully automated manufacturing process is stopped. The resulting coupler is essentially one fiber with two cores that are very near to one another.
Fused couplers are used to split optical signals between two fibers, or to combine optical signals from two fibers into one fiber. They are constructed by fusing and tapering two fibers together. This method provides a simple, rugged, and compact method of splitting and combining optical signals.