Polarization compensated integrated optical filters and multiplexers

摘要

In accordance with the invention the birefringence induced by compressive strain in silica waveguides on silicon substrates is compensated with a high index patch-such as silicon nitride-placed adjacent the core. The patch is disposed sufficiently close to the core to optically couple with the transmitted optical mode. The patch is preferably wider than the core to intersect the exponential tail of the transmitted optical mode. Such a high index patch preferentially couples TE polarization modes. By choosing an appropriate length for the patch, both strain and bend birefringence can be compensated.