偏振光束合束器/分束器用于将两束正交偏振光耦合到一根光纤中，或将一束输入光分离成两束正交线偏光输出。偏振合束/分束器大部分的应用在于将两束泵浦激光合束进入单根光纤使得功率合成，典型的结构是用两根保偏光纤作为输入，单模光纤作为输出。该器件同样可以用作分束。

Fiber Polarization Combiners/Splitters are designed to either combine two orthogonal polarizations into a single fiber or split a single input into its orthogonal linear polarizations through two fiber outputs. The most common application is to combine the light of two pump lasers into one single fiber to double the pump power. The typical configuration uses two PM fibers as input and SM fiber as output. The device can also be used as a beam splitter.