Birefringence compensation applying double-core waveguiding structures

For application in communication networks, polarization-independent planar optical waveguiding structures are essential, because the polarization state of the optical signal in an optical network is arbitrary. A new concept for polarization-independent waveguides simply adds a thin birefringence-compensating layer, which results in a double-core waveguiding structure. One of the major advantages of the double-core concept is its technological simplicity. The impact of the layer parameters is simulated and the compensating mechanisms are discussed. The feasibility of this concept is demonstrated on waveguides fabricated with silicon oxynitride technology, where the channel birefringence is tuned over a wide range by varying the thickness of the birefringence compensating layer.