Useful formulas for multimode interference power splitter/combiner design

Simple design formulas for optical power splitters with an arbitrary number of output ports (1*N) are presented. They are obtained using a model based on the interference of the confined modes of a multimode wide section. These formulas provide the correct dimensions of the device, plus the output phase relations and output guides location. The accuracy of these formulas is further demonstrated by the design and fabrication of a buried heterostructure waveguide power splitter on InP, compatible with laser integration, that yield compact and low insertion losses devices.