TE/TM MODE SPLITTERS ON INGAASP/INP

In a monolithic heterodyne polarization diversity receiver, mode splitters are required which effectively separate the TE and TM polarization of the optical wave. For this purpose, we investigated a directional coupler which utilizes a metal cladding on one of its branches to separate both polarizations. This polarization splitter can act in two distinct modes of operation depending on the degree of lateral confinement of the optical rib waveguide before metallization. For strong confinement, metallization generates an asymmetric coupler. For weak confinement the metallized waveguide is guiding for TE but nonguiding for TM polarization and negligible TM crosstalk results. © 1990 IEEE