Multimode interference (MMI) devices: a survey

Multimode interference effect and the principle of self-imaging can be exploited to create optical devices like couplers, splitters and filters. MMI devices have gained more importance in the past few years and have proved to perform better than other optical devices. This paper discusses the phenomenon of self-imaging, which is the replication of input signal at regular intervals. After that an application of multimode waveguides to power splitters and couplers is presented, followed by a brief comparison of MMI devices with directional couplers.