Mode-selective couplers for few-mode optical fiber networks

The excitation and separation of individual modes in a few-mode optical fiber network can be realized using mode-selective couplers. For excitation at the beginning of the fiber, two-core mode-selective couplers can be used, while at the end of the fiber, either two- or three-core mode-selective couplers are required for demultiplexing of the field symmetric or field asymmetric modes, respectively. Both analytical and numerical solutions are presented to quantify the mode-selective functionality.