Grating-assisted fibre optic couplers for mode-selective coupling

The coupling concept is based on a single-mode fibre comprising a grating structure and an adjacent multi-mode fibre. The working principle relies on evanescence wave coupling between the single mode and the multi-mode fibre by utilising the grating structure. Depending on the grating period an arbitrary mode of the multi-mode fibre can be coupled to the single-mode fibre.

Depending on the optical properties the novel fusion coupler may open new routes in various research fields, for example in multi-mode fibre optic communication networks with regard to mode multiplexing and fiber optic MIMO (Multiple Input Multiple Output) concepts or in laser technology, i.e. for improving the output of fibre lasers by mode selective coupling in Large Mode Area Fibers (LMAF).