Design and characterization of a mode-splitting Psi-junction

It will be shown in this paper, that the mode conversion factor (MCF) as defined for Y-junctions, can be profitably applied for the design of three branch junctions for splitting the three lowest-order modes of a channel waveguide, Accordingly, these so-called mode-splitting Psi-junctions were designed for implementation in PECVD SiON-technology, Propagation calculations point to crosstalk levels well below -20 dB at 10-20 mm junction length, The produced Psi-junctions show crosstalk of less than -17 dB, mainly originating from the nonhomogeneity of the refractive indexes of the SiON layers.