A fibre optic adapter, sometimes also called a coupler, is a small device designed to terminate or link the fibre optic cables or fibre optic connectors between two fibre optic lines.

By linking two connectors precisely, fibre optic adapters allow the light sources to be transmitted at most and lower the loss as much as possible. At the same time, fibre optic adapters have the merits of low insertion loss, good interchangeability and reproducibility. FS supplies a wide range of mating sleeves and hybrid adapters, including special male to female hybrid fibre optic adapters.