A multimode planar power splitter

A novel scheme for multimode 1 x 2 and 1 x 4 splitters is proposed. These devices differ from conventional 1 x 2 and 1 x 4 multimode interference splitters, as they do not rely on the interference between the excited modes propagating in the multimode region. Instead, their functionality is based on the principle that in an asymmetric multipronged splitter, the power in each excited mode can be directed unambiguously into one of the single-mode output channels with minimal crosstalk between channels. The geometry and relative position of the single-mode input waveguide of the 1 x 2 and 1 x 4 splitters is optimized to split the input power as evenly as possible between the two and four output channels, respectively, and to minimize the excess loss of the device. A simple low-power single-mode tap, based on the same principle, is also investigated and its excess loss and wavelength dependence determined.