Grating assisted glass fiber coupler for mode selective co-directional coupling

To keep pace with the increasing demand of transmission capacity, space division multiplexing technologies are currently intensively investigated. In this context, mode selective glass fiber couplers are of great interest due to their compatibility with existing glass fiber networks. In this work, we present a novel type of mode selective glass fiber coupler for co-directional coupling based on fiber gratings and fused asymmetric fibers. The achieved mode selective coupling efficiency agrees well with numerical simulations performed for comparison. The benefits of the grating approach are a lower mode crosstalk and a simple adaption of the propagation constants through changing of the grating-period. [661]